Beginner looking for for help

[curious aardvark]

try openscad
it works totally differently to any other cad program.
lots of information and tutorials around.

your link just looks like the sort of thing a basic websearch will turn up - or reading this forum :-)
It also mentions nothing about designing - just 3d printing. And to be honest until you've got a printer - none of that will make a lot of sense anyway.
And once you've got one - then this forum is your best help.

I started by reading a very good book: https://www.amazon.co.uk/Practical-3...gateway&sr=8-1
Now to be honest, it is a few years out of date now. But printers haven't changed that much - about the only thintg it doesn't cover is firmware. And to be honest I believe people worry too much and mess with firmware too mugh. All 5 of my current printers are still on the factory original firmware - and I've never had an issue with any of them. And they do all have different firmwares.

The book covers the basics for just about everything from printing & slicing to designing with various free packages - including openscad. Though to be honest he does kind of leap into openscad at a fairly high experience level. So that didn't help me much that way.
It is pre-simplify3d.
I'm surprised he hasn't released a revised edition.
You can have mine for a ?5 & postage :-)

where abouts in the uk are you ?
I'm smack in the middle near burton on trent - if that helps.
Happy to structure a course for you, I'm good value for money :-)

And hands on with actual printers and software is worth a lot more than a few articles online.