When you either start a new topic or in the "Quick Reply" box, there is an icon to click that looks like grey mountains with a yellow sky and a grey arrow pointing up on the left hand side. If you click this it will open a small pop up box that asks you to browse for the picture you want. Simply select your pictures and click upload. This will copy the picture to the Forum servers and put in the proper coding in the text box field.
No Problem! You should have seen my face when I was first trying to figure out the system! Once you get it to work for you the first time it goes much much smoother! :)