If you have Photoshop, you can just open the PNG file and you should have a section on your right side where you can see your layers. You can push the Plus Sign ( + ) to add a layer and move it under the Lines / Holes (if the PNG has a transparent background). And then you can import your artwork. Hopefully your PNG already has a transparent background, but if not, Photoshop can help remove the white background by using the Wand Selection Tool on the left side to select all the white space and delete and you just keep the lines and holes. Then make that new layer and then you can import your artwork under the holes and lines
You can use an app called GIMP which is free for Mac and PC if you don’t own Photoshop. It can handle your PNG file and convert it to PSD. You just have to get used to it a smidge but it’s exactly the same.
