First, log into your account.
On the Control Panel go to Quick Links, and then click on "Edit Profile." From this screen you can modify most of the things in your profile, such as your date of birth, contact information, country, etc. Note that none of those is required: all the site needs is your gender, and you're set.
At the bottom of this page is a blank space with a toolbar above it. Whatever you post here will go into your sig. This includes images, gifs, links, whatever suits you. Just be warned that sigs must follow certain rules. See the Rules thread for more details. Also, as a courtesy to other users, please be sparing with any gifs you choose to post in your sig, as members with dial-up or poor connections will have a great deal of difficulty loading the page if there are too many gifs. At the top of the page is another tab marked "My Interests." This allows you to post even more information about yourself if you wish.
