When you are posting look under the box and you will see two grey rectangles one says "post quick reply" the other "Go advanced" CLICK "Go advanced" and it will open a new page for you, now scroll down a bit and you will see a bit saying "additional options" over on the left, now click on the grey box that says "manage attachments" this should open a small window (some pop-up blockers may stop this) in the new pop-up window there are two options "Upload from your computer" or "Upload from a URL" i use "upload from computer" as that is where my pics are stored, click on the little "browse" button and select the file you want and select "open" then if you want to add another pic go to the "browse" button under the first and do the same again, once you have the pics you want selected click on "upload" button and your pics will be uploaded to your post, this may take a few mins depending on your connection, once the pics are uploaded you can close the pop-up window and submit your post
Hope this helps and isnt too long winded.
Peace and light
McBong