There are several image hosting sites to be found.
Photobucket seems to be a popular choice.
You'll have to create an acount with them, and then you can upload your photos to their server. Once uploaded, you can put links in your messages that point to the images sitting at photobucket and they should show up in your post.
I've never used photobucket or the like because I have access to my own severs to host any files I want to share, so I can't really guide you as to how it exactly works. But I'm sure you can find good directions on their website.
Also... you can check out
this post (Posting Pictures to this Forum) for instructions on posting pictures on the forum.