Copywriting is what people in advertising do. Registering a copyright is what creators do to establish certain valuable remedies (including damages) for the infringement of their work.
I'd like to clarify this, because it is a constant source of misspeak when I give lectures or appear on panels. A copyright subsists from the moment a work is put in some permanent form in which it can be seen, read, perceived or otherwise experienced by others. With a photograph, either digital or analog, that moment arguably is at the point when the shutter is released. There is still a difference between a published work and an unpublished work, but, make no mistake, putting it up on a website is publishing these days.
There are specific forms for the registration of copyrights, depending on the form of literary, visual, or performance art to be registered. The Copyright Office has an excellent website to guide a novice registrant and provide the appropriate forms needed. Check it out here.
Photographers generally use form VA for registering physical copies or use an electronic registration process, which I understand is fairly slow and frustratingly old technology. My only experience with it found it so and I just finished reading comments gathered by the American Society of Media Photographers (ASMP) for submission to the Copyright Office on its proposals for raising registration fees which support this impression.
ASMP has long been the leading organization working on behalf of photographers' rights. I spent two years on the ASMP national board of directors and chaired the Rights Committee after Richard Weisgrau, the long-time chair, left the board. ASMP has forged an excellent working relationship with the Copyright Office and members of Congress, and has earned a place at the table when copyright law is considered. Naturally, it has stepped up to present the concerns of photographers who face steep increases in registration fees if the new schedule goes into effect.
Photographers register more discrete works at one time than any other creators, and digital photography has increased this output. Protecting remedies to infringement by registering work in a timely fashion can be expensive, even with group registration. (As an aside, this is an issue that goes back to wet-plates, according to some old cases I have read.)
Because photographers need to distinguish between unpublished and published works when registering copyrights, I have recommended to clients that they set up a workflow that permits them to register all unpublished work created within a 60 day period and separately register all worked published within a 60 day period. They can be the same periods of time, but they must be registered separately.
The 60 day period is because a copyright registration that is made within 90 days of creation or first publication gives remedies for any infringement that occurs within that window prior to the actual day the registration is made. 60 days gives the photographer a pretty good window to catch an early infringement.
Note: in the U.S. a copyright registration is necessary to gain access to the courthouse door. It is not necessary (but certainly helps) to establish copyright ownership. If a creator has not registered a work within the appropriate window, the creator cannot ask for statutory damages (currently as much as $150,000 per intentional infringement) or for attorneys' fees (which is usually the key to an attorney's services in an infringement.) More importantly, a timely registration is what stands between a quick settlement and expensive litigation which might not be worth the trouble if "actual" (what a photographer might have charged for a licensing fee if asked in advance) rather than "statutory" damages are what will be the basis of determining loss.
A creator who fails to register copyrights in a timely manner will still have to register in order to gain access to the Federal Courts, which, currently, are the only courts of jurisdiction for infringement actions. Most of the time, if case is about the usage of a licensed image and the use made is greater than that of the contract, that case will end up in Federal Court rather than in a state court because a defendant will ask for removal with the hope the plaintiff hasn't made the appropriate registration. It is best to be ready for Federal Court at the onset. I have filed complaints where the client was in the process of getting their copyrights registered, which is disclosed in the papers filed. Some courts will permit matters to move forward, allowing the complaint to be amended when the certificate of registration is available, but this might not always be the case. There is a special form which must accompany a copyright complaint, which, I recall, asks for registration numbers.
At the last talk I did, the moderator asked for ways to protect works of authorship. Two offered were to register with the Writers Guild of America (WGA) or to send a copy of the work to yourself through the mail.
Neither of these methods register a copyright and neither will get you statutory damages or attorneys' fees. The WGA registration, which is actually touted as a way to protect ideas (copyright does not protect ideas, only expressions of ideas), is used to help establish first-in-time scripts or elements of screenplays. A timely copyright registration for a screenplay (make it before sending it out to readers) will do that as well, plus preserve those lovely remedies of statutory damages and attorneys' fees.
The other method, of mailing a copy of the work to yourself and putting it unopened in a drawer, is sometimes called "poor man's copyright." IT IS A WASTE OF TIME. I'm not even sure it was effective for anything under the 1909 Act, but it is totally ineffective under the 1976 Copyright Act. The 1976 Act eliminated all state-level copyright protection, established a term of copyright protection based on the life of the author (while a different time frame was established for "works made for hire"), and established the Federal Courts as the only venue to hear claims of copyright infringement.
One final note, in the not-so-distant past, creators relied on the copyright registration of a magazine or book to protect their individual contributions therein. Unless you are the only author of the book or magazine (unlikely), you must register the copyrights for your contributions separately to preserve your rights. If you are the only author of a book, you should, by contract, make sure that the copyright registration will be made on your behalf, in your name, by the publisher. If you make a contribution to a book which has works by a number of people in it, make sure your reserve your copyright rights in your contract with the publisher and make your own registration of the contributed works. If you provide work to a magazine, make sure you register your contributions as published works. If you were able to register your contributions as unpublished works originally, registering them again when they are published is a good business practice (though not entirely necessary.)