Here is the easiest way I know. Open the picture and resave under a new name so you don't lose the original. Open the renamed picture in "paint" if it is a windows based computer. There is a "resize" option at the top. In the version of paint I have it is right next to the "select" icon. You can resize by percentage or by pixels. Then save the picture. Make sure the total size is smaller than the moparts limit. Hope that helps.