By Miles Nicholson
The image that you wish to place on your part should have a transparent (alpha channel) background. It should be an image file that supports transparent backgrounds e.g. PNG.
e.g.
Select and select the face for the sketch
Select Sketch ribbon tab > Insert panel >
Browse to your image and select
Position accordingly
Right click on the image >
Select Use Image Alpha
Select
The background part colour will now be visible through the transparent section of the image.