We have a similar one and we do text in photoshop, save as JPG and then open with the machine software.
The good thing about using photoshop is that you can choose from a wide variety of fonts. We engrave letters on leather and set the and we set the resolution in photoshop to 100 pxl. If set it too high or too low may result in bad engraving from my experience. Though I donīt know in other material how it works. Then you have to try with different speed and laser beam power to see the best results.
You have to be careful with your eyes when using reflective materials with the laser beam and donīt try to see directly.
Hope it helps.