Ahh, that's where the "machinist" comes in. Unless it's fairly simple geometry which can be hand coded, you'll still have to select the cutting strategy (pocket milling, profiling etc),then select the contour(s), select the tools, speeds and feeds. CAD/CAM has still not evolved to the point of where you just draw it and click the G code button. There are just too many variables/nuances involved in deciding how to manufacture the part.
Take 10 machinists, and give them the same tools, and each one will manufacture the part a little differently. Some will make it fast, but not accurate, and some will take longer and produce a more accurate part. Ther is no one "right way".
So, check out some of the free demos for some CAM software, and run them through their paces (try before you buy). If you are reasonably mechanically inclined, you'll pick up the process pretty quickly ( 2D stuff in less than 40 hrs with some prior CAD skills).
regards
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Can't Fix Stupid