Adding songs to my iPhone from my iMac

Hello all,
I have a folder on my Mac with some songs in it. I would like to put these songs onto my iPhone. How would I do this with iTunes? If someone would give me some simple to follow instructions on how to do this, I would really appreciate it. I never learned how to use iTunes on windows, so I’m coming at it brand new on the Mac. The folder of songs are in my music folder on the Mac. Thanks in advance for any help with this.
Take care,
Lisa