To post pictures, you have to go through two main steps.
Step 1- Upload picture
1. In the blue bar at the top of the page, click on the "uploads" link
2. On the upload image page, find the browse button. Click on the browse button.
3. In the new window that just popped up, you will see your files on your computer. Find the file you want to upload and select it
4. If you want to change the size to website or message board, select that from the pull-down menu and make sure to check the box.
5. Hit submit.
Your image is now uploaded and an html tag has been created. Copy this tag. The way I do this is to highlight the link and press control and c at the same time. This is a shortcut for "copy"
Step 2- Post picture to thread
1. Go to the thread where you want to post your picture.
2. Hit "reply"
3. Now paste your picture to the message. I do this by pressing control and v at the same time. This is a shortcut for "paste"
Your picture will appear as an html code, but will post as a picture.
Hope this helps!
eta: correct spelling and code