First of all, you don't upload pics to RHP. You have to host your pics somewhere else on the web and then keep those URL's handy...
There are 3 places where ou can have pics - Profile, Forum and Clan.
Check the top red navbar, you'll see a My Settings link. Click the relative link for Profile or Forum (Clans work differently, in the clans section, you have to use the Edit My Clan link).
You will see a textbox where you can then enter the relative URL.