On a mill Mach3 is not complex, once you have the ports and pins set and the movement callibrated and jogging working the complex part is making it cut parts.
Whilst many will baffle you with BS by suggesting you learn to code parts manually that is, in the current climate, an utter crock. You should learn G-Code so that you can see what your machine is trying to run but a decent CAM system will allow you to generate code to make parts which you could never hope to hand code.
Simple 2D and 2.5D parts are so simple with decent CAD/CAM that the work required will measure in minutes, and rarely out of single figures,

- Nick