Does anyone know of any good sites to make a banner for my signature?

Alot of you have such lovely signature banners and i'd love to try and make one myself, but am not sure where to start I've been round the net, but got nowhere.

Can anyone help?

Not a clue about websites, sorry

Hx

Thanks Helena, i'll have a fiddle about first and see what i can do. I need to get some good shots of them first aswell Which is hard to do with Buddy cause he doesn't stand still long enough