History on Green Day

Billie-Joe Armstrong, Mike Dirnt & a drummer called Al Sobrante (His stage name) formed a band called Sweet Children.

They changed the name to Green Day and Al Sobrante left.

They found Tre Cool and he started drumming for them

Green Day is named after their love of marijuana.

Mike originally played guitar but they couldn't have to lead guitarists so he switched to bass, the first beat he played sounded like dirnt, dirnt, dirnt, dirnt.

That's how he got Mike Dirnt.

This is a very, very brief history.

But your question was brief and you didn't say specifically what you wanted to know.