there are several image hosting sites along the lines of photobucket.
Hosting photos on the forum itself bogs the forum down, and limits the size of images you can post. By hosting your pics off site you not only save OCC some bandwidth, you get the liberty of posting full size images, in the part of your reply where you want them.
If you look at my 1450 project thread (which is long due for an update, I know) you will see what I mean. It's a lot easier on the readers to post pics in the response, so you can caption the pics as you go. If you attach them through the forum they just end up stuck at the bottom of your post and it can be difficult to determine what you are trying to portray. Not to mention small pics are no fun.
I use
www.imgur.com and photobucket. I like imgur because you are not required to set up an account, or remember any passwords. Upload your image to the host of your choice. Come to the forum and right above the box where you type your reply you see an icon of a picture with a couple mountains in it, it's yellow. Right click> Copy the direct link for your image from the image host you used, and then click the yellow picture icon here. Right click> paste the direct link into the box that appears, click OK and you should be good to go. May take you a couple tries to get it down pat, but that is why just about every Vbulletin forum has a testing area.
Happy cubbing!