I downloaded 2 skins today. One of them was a 2 layer skin and the other was just a simple single layer skin. Is there a way to combine part of the 2 layer skin with the single-layer skin?
You mean like use just the second layer of the first and use it as the second layer of the second skin?
They're just pictures so you can use a picture editor, you just need to keep the size of the picture and the position of the skin in the image.
Oh, and the background has to be completely transparent.
The Wiki page shows where in the image each piece goes:
And there are skin editors that let you see how the skin looks on your character as you edit it.
(From the Wiki page, I haven't tested any of these myself.)
i want to use the first layer of the first as the second layer of the second
edit: I want the second skin to become the second layer of the first skin.
Looking at the first and third images at the bottom of https://minecraft.gamepedia.com/Skin
Cut out the "Head" bit of the second and paste it over the "HEAD2" of the second first.
Cut out the "LegBodyArm" of the second and paste it over the "RL2 BODY2 RA2" of the second first.
Cut out the "Leg" and "Arm" of the second again and paste them over "LL2" and "LA2" of the second first. Ooops!
If the arms and legs aren't symmetrical then one or more of them might have to have the "OUTS" and "INS" sections switched.