I presume you already know that you write a profile by going to the User Control Panel. If you want to add pictures to your profile, you do exactly the same as when you place pictures in a post (as described already).
Only, because there is no preview possibility when writing your profile, you can't actually check whether you have done it right. So you keep seeing [IMG] and [/IMG] tags, and you have to add those tags by typing them. There are no clever buttons to help you to add pictures when you are editing your profile.
Only after uploading your profile and opening one of your own posts, you can see whether you have done it right. In the User Control Panel you won't see the pictures at all.