I think you don’t need to change the images to vector in order to engrave. Draw the image in black and white only. In the iOrnament app, find the button that allows you to export; it’s a camera with an up arrow. Put the part of your design that you want on your screen and do export image. You can edit it with whatever photo editing software you use to trim off the parts that you don’t want to engrave. Save it as a png or jpeg and upload it to the glowforge app. Let us know how it goes.