You don't need to copyright anything; people rarely do as theft of intellectual property is so rare; writers have enough of their own ideas to be going on with.
But if you insist on it, put your identifying details on whatever you want to copyright and seal it in an envelope and post it to yourself, snail mail, and make sure it's post-dated. And don't open it!
This is not viable in court. Ask any attorney. If not for the sake of dispute why would you do it? So it is a waste of a stamp. It doesn't hurt anything either. It is a null effort.
You can obtain copyright forms online and print them yourself. I saw many sites just by Googling copyright forms. I think I used the short form:
http://www.copyright.gov/forms/formtxs.pdf Fill it out, send it in with your printed work and a check. You’ll get a receipt in about a month.
As for the ongoing argument as to whether you should or not: it cost $35 to copyright a novel. If you copyright your work and there are revisions upon publication it will cost another $35 to resubmit but there is no penalty for submitting the same material twice. At worst you have spent $35 you might not have needed to.
There is no need to tell anyone that you’ve registered your work. I will tell my publisher so he can examine my forms. If I didn’t do it the way he wants it can be done again.
It is unlikely that you will ever need to prove your copyright but the fact that a copyright exist says there is an absolute chance that someone will have to prove their copyright. Will it be you?
A copyright is automatic when you put your words to the page. This has absolutely no validity in a courtroom without evidence that those words were yours. The strongest evidence is the receipt from the copyright office.
I will not submit electronically without having first applied to the copyright office. I do not fear the recipient of my submission. I fear the fact that anything sent through the internet can be intercepted either unintentionally or deliberatively and easily reproduced, edited, or publicly displayed. I fear the opportunist that might happen upon my unprotected labors. Across the months or years you will spend submitting, how often will your work cross within reach of someone that is capable of benefiting from your effort?
If I acquire your unprotected work, I can send it to the copyright office under my name and you would have a hard and expensive battle to reacquire your rights. The odds of me getting hold of your work is so small but if I wanted to get hold of unprotected work it would be easy, and though it likely wouldn’t be yours, it would be someone’s.
I am not familiar with anyone on AW disputing a copyright but I am familiar with some that have found unauthorized sales and display of their work. The copyright office receipt is your license to kill.
I find the idea that “your work is yours” a little foolish. There is occasionally plagiarism but I don’t worry about another writer stealing my idea. Their book won’t be my book. Sure, there are lots of ideas and some are even similar. A copyright is no help in that. I worry about the non-writer that is too lazy to earn his own living, the thief, the predator, the immoral, the opportunist. These people are not in our business and they don’t care about you. If you want to go with “the chance is so slim…” than you might as well throw out the smoke detector, stop using your seatbelt and cancel your home owner’s insurance.
For the price of a daily cup of coffee for a month I have peace of mind. There is no detriment to having that receipt. Am I paranoid? Maybe, but there are writers who don’t have it and wish they did. I will not be one of them.