On the E string, at the 6th fret.
On the A string, at the 1st fret.
On the D string, at the 8th fret.
On the G string...

Oh, you mean a Bb chord? ;)

XX3331

Or if you can curl your thumb around with enough purchase and strength, stop the two bass strings at the 1st fret.

I just go with a 4 string chord there or else barre an F-shape at the 6th fret. There are other variations too when you get away from first position chords.