first you write the greeting and the day and date, example: dear friend
on Thursday 3/6/2021 I’m writing you this letter etc..
then you write them how they are !
and then write down what you want to tell them, whether talking about your day, your work, your plans for the vacation and so on ..
and then you end it with hugs and kisses ( xoxo ) or what ever you feel comfortable with, and goodbyes and lastly write down your name .