I do inhale for 4, holds for 4, exhale for 6. I don’t know if it really matters, I imagine the main point is to be mindful and come back to the present by focusing on the breath. I can’t remember why breath retention is a good thing to work on 
@pinkandblue There are links to some more meditations here which might be worth a try:
https://talkingsober.com/t/meditations-for-recovery/362
I use a meditation app called Calm which I love. Others that seems to be popular are Headspace and Insight Timer. And of course there is YouTube!
And also agree that going outside is good. I do a lot more walking now which helps clear my mind.