Im New and Confused. Help Please!?!

[Blackfoot]

I would like to join a pack please.

And I have edited my existing avatar to look like my character just wondering what TYPE of picture can I have?

I have tried making it a GIF and JPEG. But they won't work. I wondered if any of these are allowed?

-PNG
-BMP
-PDF
-TIFF

Thanks for your help

Blackfoot x