I'm trying to add an avatar and I have one that fits both requirements. When I add it it says 'invalid file'. Then I read that you have to be a member for 20 days with 20 posts to use the signature option. Does that include an avatar? Or am I just doing something wrong?

no you should be able to upload an avator. i'm a newbie too. and uploaded an avator.

thats strange that its not accepting it. if the pixels and file size are met.

It worked when I tried it again!

Sometimes it just needs a little shove . Congrats on getting it to work for ya