Engraving is the act of carving out a shape or symbol into a material. Engraving is similar to etching, but engraving is deeper. A number of different items, from metal to wood, can be engraved both by machine as well as by hand. If you want to engrave letters into an object then you need to carefully lay out your plan and practice a bit to be sure that the engraver you're using works with the material you want to engrave.
Mark on your practice material, which should be a sample of your final engraving material, with your marker. Draw out the letters you want to engrave, and make sure that the style and shape of the letters is exactly the way you want.
Engrave the letters with your engraving tool. The engraving tool is basically a miniature, hand-held jackhammer. This means that you need to hold it steady while it gyrates, and allow the head to chip away the material to carve out the letters. Engrave so that you have a smooth depression for each letter and that the letters look exactly how you want.
Repeat this process on your main material. Once you're used to the material and you have the design set, engrave the letters again, this time on your base material instead of the sample.