There are two things you need to learn, the first is the mechanics and use of your machine, and the other is your programming software.
I assume your using mach3, you'll have to figure out how to jog, set axis values to zero, load and rewind g-code, and you have to learn the capabilities of the machine, what bit do you use for what material, what are the spindle and travel speeds? Hoe deep can you cut in one pass,
I also bought a cheap chinese 3040, the first thing was to replace the wimpy spindle motor. I bought artcam express, for $150 it does everything you need. Highly recommended.
With this machine I have done some nice v-bit carving in pine and maple and high density urethane, as well as some 3d reliefs.
F-engrave is freeware and is good for v-carving or engraving lettering, you can also v-carve bitmaps.