You have to make the picture in some program like Paint.net, Photoshop maybe, whatever else people reply with. Then you upload it to a photo site like www.photobucket.com and then put it in your signature (in your profile under forum options) with (img) and (/img) around the link, but replace the ( ) with [ ].
I can help you make a signature. Just tell me what yoyo you wanna put on it, what words you wanna put on it, and what kind of background you want. (colors, theme etc.)
That’s what the Thank You button in the top right corner of each post is for. Please use that instead. Thanks.