If you click on '
reply' (as opposed to the usual 'quick reply') at the bottom of each page - you will be able to click on the "
Enter an Image" icon - fourth from left (above and on that screen.)

Alternatively, you can click on the "
Switch to Full Reply Screen" whilst using the Quick reply screen to get to the enter image icon.
Or even just use this code

[img]http://ADDRESS TO IMAGE HERE[/img]