Trevor-
On most forums, if you want to post a photo, it is necessary for that photo to already be resident on a server somewhere. There are numerous websites that provide that service for free. Perhaps the most popular of them is
www.photobucket.com.
Once you have a photo uploaded, and know its address, then it is only necessary to properly surround the address with markup language wherever you want it to appear in your post. This takes the form of
{img src=http://...whatever.jpg}
except it is necessary to use square brackets rather than the curly brackets shown. The left square bracket is one key to the right of the letter P on the keyboard.
Alternatively, although I have not personally used this method, it is my impression that if you attach photo(s) to an email to Jason, he will upload the photos for you, and create a post that has the photo(s) in it. However, now that Jason is busy with graduate school, he likely has less time to do things like that, so I would recommend using the first method.