Upload your pics to the Autopia gallery or to an online photo hosting service like Photobucket.com, cardomain.com, imageshack.com, etc...
Find the URL of the picture and copy that. Paste it into a thread here, and add IMG and /IMG in brackets [] before/after the URL. The pics should then appear in the thread. At Photobucket you can get the URL in brackets already so you don't even have to do that part.
