The joy of quartetting!
You don’t have to read music or understand music theory to sing barbershop. Barbershoppers are really welcoming of newcomers, and they have CD’s of your part being sung that you can learn from (which is the method I prefer.) If you’ve ever wanted to sing barbershop music - perhaps in a group so you don’t stick out while you’re learning.
The melody is sung by the lead; he’s the center of the audience’s attention when a quartet is singing. The tenor is above the lead, often singing the kind of harmony that people improvise in casual group singing. The bass sings the low notes, often dramatically low ones at the end of phrases. The baritone sings between the lead and the bass, singing notes that people aren’t normally aware of but that are essential. This makes the baritone part sung alone sound strange because it doesn’t match either the melody or the normal harmonies that people are used to hearing.