CAD Advice

[tk007b]

Hi all, Only after advice! ;-)

Just spent hours and hours getting nowhere fast with some minor adjustments to a couple of objects in an STL file. I have spent a lot of time looking at:-
- Fusion 360
- OpenSCAD
- Google SketchUP

but without much success (out of the 3 sketchUp was the one that I made some progress on). My questions are:-

1. For a complete (and I mean complete) beginner, which CAD software is the easiest to learn. All I really want to do is to be able to make amendments to existing .STL files for now

2. Which resource should I use for a guide I have included a help.zip file with the files and a !Readme with what I want to do.

Not expecting anyone to do it for me, but just to give an idea of what I am trying to achieve.

Thanks very much

TK :-)