It looks like most other standard sheet music. The most common style for an instrument such as a clarinet is known as the 'Treble Clef'. There are 5 lines, which gives four spaces for the composition to be written.
The Bb clarient is the most commonly used clarinet
Clarinet is most commonly used for marching bands, classical music, and jazz. It is also sometimes used in blues, rock, bluegrass, and country music. It is also very popular for commercial jingles and theatrical music.
The most famous clarinet works are the Mozart Clarinet Concerto and all the Weber Concertos.
Arguably, Mozart's Clarinet Concerto.
folk
You can transpose flute music for clarinet music. Flute is on concert pitch, most clarinets are not. Example: A flute's Bb is a clarinet's C. Bb= B flat
the blues
There are bass, soprano, and alto. But there are more than Three sizes! There is the Eb soprano, Bb soprano (most commonly seen), Alto clarinet, Bass clarinet, Contra-alto clarinet, and contra-bass clarinet. There is also an A clarinet!
Clarinets are most commonly made of plastic but good ones are made of wood
I would say the most popular music style of 2009 is R&B.
A person can find the clarinet first score for Molly on the Shore through a website called Score Exchange. Sheet music can also be obtained through most music stores.