How the heck do I get my book and Amazon link into my signature?

OK - I'm trying to put my self published book into my signature line.

I've been reading the FAQ and trying this and that - and links and SIGPICS and all I am getting is an invalid file message. Feeling kind of dumb now.

I am thinking that if I had the code for someone's book, I could just insert my particulars and maybe that would work.

Anyway - any tips on this?

Thanks so much...