Here is a guitar chord chart for the key of Bb major. Since your major and minor keys share a key signature this will also be the chords for G minor.
The key of Bb will be a lot of bar chords on the guitar. If you don’t know your bar chords and still want to play in the key of Bb just capo on the third fret and use the G Major Diatonic Guitar Chord Chart. When you capo on the third fret and play a G major chord shape you are really playing a Bb major chord.