Basically to post a pic you need to do these things...
1. Find somewhere online to host (upload) your pics. I use Image Station ([url]www.imagestation.com[/url])
2. After you have uploaded your pics, right-click on them on the site (my photo album at Image Station) and copy the line that says "Address".
3. Go to your post, and wherever you want to post the pic in the text put this [i m g](right-click paste here)[/ i m g]. Make sure you leave out the spaces to get img and /img.
4 Your done!
Here is an example of my pic.
[img]http://www.imagestation.com/picture/sraid75/p41887bd1596b9054908fb8285c6a6ae9/fb47f7fe.jpg[/img]
To get that I put this in as text [i m g]http://www.imagestation.com/picture/sraid75/p41887bd1596b9054908fb8285c6a6ae9/fb47f7fe.jpg[/ i m g]. Of course I did not use any spaces.
Hope this helps!