If you think this is hard you should of played CK2!!
But yeah it has a extremely steep learning curve even if it's been streamlined from CK2.
Definitely do the tutorial that explains the absolute basics there is also a really good encyclopedia in bottom right hand corner of the screen which explains a lot of things.
For an absolute newbie start in Ireland 1066 and the county of Munster. Good start as England, Scotland France and Norway (who are the major European powers at that time) are all at war so they don't bother with Ireland for around 50 which gives you a good head start. Main goal for Munster is for the unification of Ireland which is pretty easy and you can do in around 25 years.
In my first game I did this and Norway won the battle of England beating Harold and William the conqueror so I formed an alliance with them and we both attacked Scotland then France.
Take your take and sort out your council. I can't stress how important this is. I spent nearly 2 hours sorting all that out before I even pressed the unpause button. Getting the right people in your council can get you insane bonuses like extra tax and better soliders.
Remember your playing as a family not a country think about the future all the time.
Alliances can be fantastic to help the future of your dynasty but picking the wrong one can be fatal so choose wisely and again think about it carefully.
You are going to fail. A lot. Learn from the mistakes.
Just a few tips but just practice. I found CK2 almost unplayable first few goes as it's so complicated however I just stick with it and then something just clicked then I was hooked.
There are some really good YouTubers who give really good advice and I learnt a lot though their playthoughs.
Quill18
Many A True Nerd
ItalianSpartacus
Really good for learning the game