To start the pattern you only cast on one stich. (In row1) I just update the pattern with that information
I put the number of the rows after finish the hat, so can be small mistakes. But you don’t need count the rows if you are counting the stitches.
All even row is purl.
It is a easy pattern that I am sure you will enjoy it.
If you want to use yarn with a bigger weight, you can follow the coments of rsk