As Jonathan says what you already have downloaded is really just cam software to produce the G code, yes they have some basic cad functions but they are basic & if you are looking for something with better drawing tools then you need to look at a proper design or cad package.
Do the design work in a vector based drawing program then import into cam software as dxf, eps, ai, pdf or what ever file formats can be imported.
Generate the code in the cam package & export to Mach3