I have bought a Used 3 axis CNC/router. I am going to use the 2.2kw Chinese Spindle and VFD.

Please can someone advise me to which 2D design software to use with Mach3 ? I would also like to use free online Cad files to make stuff too, so I guess I need software that converts these files to G code ?
Please bear with me, I am new to CNC/router software.

I want to mill small pieces of Alu and wood and engrave some work.