I want to make a signature, but I don't know how. I went to my profile and it just said 'Signature' and then a blank area.

Hit the click the text that says "edit profile" on any of the horizontal blue bars in your profile. It will load a page where any text you can edit, including your signature, turns to a white box. Type what you want for your signature in the two boxes for signature (one box for each line) and then click "save profile" in any of those blue bars.

Oh, wow, I'm stupid. I didn't see it at first. Thank you for your help! ^^