nasser ... first you have to disable rich text first on the botom of the box.

Next you click that green plus sign ...

Then you will see another window popping up ... , on the top of that new window click 'upload'.

Once you click 'upload' the window will change with 'browse', choose whatever file you want to upload then click 'preview'. After that click 'submit'.

Once you click 'submit' after the photos uploaded to the site you click 'insert'.

You will not see the photos on the box, you will only see some kind of code. Once you post your post then you will see your pic.