Press the User CP button. Its below the banner.

Then click edit profile. At the signature write this: [img]*[/img] where the asterik is the location of the image/signature.
Usually a website where you have hosted your image. Host the
image on www.iownjoo.com

And for the avatar click on Edit Options then scroll furtest down on the page and click on change avatar. Uppload it from your comp or from a website.