PMD Editor can be simple to use... but it can sometimes be a pain in the butt.
The easiest thing to do in PMD Editor is to change the colors.
When you open PMD Editor, two windows will pop up. One window is the "editing tools" window. The second window is the "model preview" window. In the editing tools window, go to the fourth tab. You can change the colors in there.
Once you are in the fourth tab, select a "layer". Now you choose the colors you want it to be.
When you change the colors of a layer, a part of the model you are editing will change color.
If the "changing colors" is confusing to you, I'll make a changing colors tutorial tomorrow, considering it is 9:38 at night.