How to play don’t stop believing on guitar

What key is don’t stop believing in?

E major

What is Bb chord?

The Bb Major chord is a common chord on the guitar. It is the 4th chord in the key of F (a very popular key), which means it get used quite a lot. The most common ways of playing it are on the first fret as a root-5 bar chord and on the 6th fret as a root 6 bar chord.