Just learn the hands and what beats what.
All hands are made up of five cards, youre two and the five in the middle
High card- having just a high card like king or ace
Pair- two cards of same number
Two pair- having two of one number and two of another
Three of a kind- three cards of same number
Straight- five cards in numerical order of any suit
Flush- five cards of same suit in any order
Full house- 3 cards of same number and 2 cards of same number together
Quads- 4 cards of same number
Straight flush- 5 cards in numerical order of same suit
Royal flush- highest possible hand. A straight flush that is 10,J,Q,K,A
The rest is just up to you. You can play tight and only play strong hands. Or be loose and try to bluff weak hands. Ideally you do both so you arent predictable.
Theres also more complex stuff on how to play but thats only if you wanna play pro. Just playing casual with friends doesnt require that level of knowledge