Movable Chord Shapes
Time to exercise your brain instead of your fingers! Check out the chart below. All major chords are built with the root (1), the 3rd and the 5th of any given major scale. When you lower the 3rd by a half step, you've got a minor chord.
When you add a flat 7th to a major chord, it turns into a 7th chord. And finally, when you add a flat 7th to a minor chord, yes, it's a minor 7th chord!
So here is a major chord that you all are familiar with, I hope...
Lower the 3rd by a half step, and you've got a minor chord.
Add a flat 7th to a major chord, easier yet, lower the root (1 or 8) by a whole step and you've got a 7th chord.
Likewise, you can lower the root by a whole step from a minor chord and here is minor 7th chord.
These chords are movable, so you can play them anywhere on the guitar neck. If you want to play some F chords, just find out where the F is on the 6th string. F happens to be on the first fret of the 6th string, so now you can play F, Fm, F7 and Fm7 chords just by playing all the chords above on the first fret.
If you want to play these chords in B, play them on the 7th fret because that's where the B is on the 6th string.
You can do the same with the chords with the roots on the 5th string using the following diagrams. Same idea different strings.