hangster , see the first post by Brad , it shows various links.
I use photobucket. I transfer (upload) my pictures into a photobucket acct then click 'direct link' once I enlarge each photo.
When replying on rvnet , I then click 'post a reply' (you'll see the 16 icons in the reply box)
use the square yellow picture icon when I want to 'post a reply' showing a picture . Limit your size to , I think its 600 width . You only have to put in the width. You can click the 3rd icon with the magnifying glass to 'preview your picture before you post it .
http://www.rv.net/forum/index.cfm/fuseaction/thread/tid/14122053.cfm