Re-formatting a portable hdd for Mac.

I am looking to buy a portable hdd (WD My Passport Ultra 1TB or similar). All the reports I have read state this type of hdd can be formatted for a Mac desktop but no where does it explain what to do. As a techno dinosaur I need this process to be easy and explained one step at a time. Any volunteers?

google 'Mac format drive' results

2 of the top 3 hits - 2 methods - both will work - I personally use the 2nd
https://support.apple.com/en-us/HT201909
http://knowledge.seagate.com/articles/en_US/FAQ/207851en?language=en_US


or a youtube video in the top 10 hits
https://www.youtube.com/watch?v=LN5my4Lrd-4

Thanks for the assist, I'll be back one way or another!