Well, you should be able to do it with existing programs Kev. Megabytes or kilobytes aside, your original pics have now been reduced by someone to 1/6th of their original size, though they could have been made even less memory intensive.
We really don't want you to leave the GB over this. Do you have Microsoft Paint on your machine? If so, and depending on the version, you can open your picture in MS Paint, select "Resize", then in the window that opens, press the "Pixels" button, type in "800" in the width box and hit enter. Then save the picture and select jpeg when it asks. Easy Peasy.
Keep trying. We can walk you through it.