Step 1:
Locate the picture. Right click, go down to 'Copy Image Location'. If you don't have that choice go to 'Properties'. A window will pop up. Find where it says 'Image location' Copy it.

Step 2:
Go to 'User Cp'. at the top. Go to Edit Profile.

Step 3:
Put the Tags [IMG] [ /IMG] (but w/o the space) put the Image location in between them.

Then just click 'Submit Modifications'