First: I reallly like the avi and sig you made.
I think you can upload the avatar directly but you have to upload the signature at another place and store it somewhere on the internet. You can use photobucket.
Then go to "edit signature" in "my controls". Then you have to insert the complete address of the picture (the place where you have uploaded it before) and wrap it in a IMG tag. (don't forget to close it)
It should work then.
Do I make sense?
Ulli