A few people have been scammed on the site, Only use paypal to pay for items for sale by other members. If they will not use paypal, its likely a scam NEVER SEND E-TRANSFERS OF ANY KIND.
Click on 'Share' and make sure that button is selected that says 'BBCode'. Select the size you want from the drop down and copy the text in that box. When you paste that into the forum your picture should appear.