for a new thread, you just click on manage attachments, and then there are 5 slots for uploading photos. On a regular post, after you type whatever you plan on typing click go advanced and then do the same thing as above clicking on manage attachments. Must be a jpeg or bmp. Now normally I wouldn't say this, but like most forums their is a section that offers tips on how to do things like posting a pic, video etc... We happen to have one labeled Website Suggestions, tips etc... when you click into that forum your answer is about 7 threads down.
http://www.wakeworld.com/forum/showthread.php?t=777301