Measurement is a important things when working with CNC's and also Metal in general. Here is a great introduction to measurement lingo you might her when working with metal
https://www.mitutoyo.com/wp-content/uploads/2015/11/EDU15001A.pdf
Squaring Stock
The feeds and speeds on this video area little questionable, but the concept is good
Tool Library Link (Always double check the tools as they can change on occasion)