To post a picture.
If you're in "Quick Reply", click on "Go Advanced"
If you want to add a picture scroll down below the submit post button and look for the manage attachments button. A small pop-up window will appear. Click that to browse to the picture on your computer, and hit the upload button. Wait until the "Uploading Pictures, Please wait" goes away. You'll also know it's done when your picture is listed in the "Current Attachments" section on the pop-up page. Close the pop-up window when all attachments are done.