You can try jsu pulling it in by drag 'n drop but the most relaible way is as follows
Log in
Go to USER CP in the yellow bar at the top
Goto PICTURED ALBUMS in the side bar
ADD Album
Upload Pictures - and then find picture and add it
Once its there click on it and it gives you either an html or a bb address - copy (I use the bb version) and then back to this forum
Open new post hit the little yellow square with sun and mountain and insert the bb code