I decided at the age of 20 to learn the guitar and starting writing songs almost immediately.
I found not knowing much quite helpful .. I tried working out songs I liked and through my incompetence ended up with something else.
The basic structure was there so anything I did over the top held together but sounded nothing like the original starting point.
Lyrics were easy .. being young I had plenty to say.
I am now 59-years and I still perform some of these early songs.
I think Garage Band is fantastic for learning about arranging music and developing musical ideas.