Once you've mastered playing A-based major barre chords on the guitar, you'll find learning A-based minor barre cords a breeze. You don't need to do the strange finger contortions for the minors that you had to use for the A-based major barre chords.
To form an A-based minor barre chord you could follow steps similar to those you used to form major barre chords based on A: Play an open Am chord using a 3-4-2 fingering instead of 2-3-1; lay your first finger down across all the strings on the other side of the nut; and then slide the shape up one fret and press down firmly, producing a Bbm chord.
On the other hand, you can make things easier for yourself by skipping the “sliding up from an open chord” process and just placing your fingers directly on the frets, as indicated by the following chord diagram. Check your strings individually to see that they’re clear and buzz-free.
With this basic barre chord structure, you can now play a minor chord in all twelve keys just by moving your left-hand position up and down to different frets. The chord name will be the name of the note that you play on the 5th (A) string.
Try putting your major and minor A-based barre chords together. The following progression is typical of a rock, folk, or country song and uses both major and minor A-based barre chords.