It’s probably a raster type image, and those can only be engraved until you create vector paths for the machine to follow. 
You have a couple of options.
If you want to do it in the Glowforge interface, you can use the Trace function to create cutlines around the pattern elements.
Or you can use the auto-trace ability in any 2D vector based program to create your own cutlines before saving the file as an SVG and bringing it into the Glowforge interface.
There are a series of tutorials in a spreadsheet called the Matrix that will show you how to do it for whatever design software you choose to use.
If you’re completely new to laser cutting and vector design, I’d highly recommend starting with the tutorials at the top of that spreadsheet - they explain a lot about using the interface, and will wind up saving you a lot of time in the long run.