The beauty of Barre Chords is that they use a Movable Chord Form. Once you learn them, you can play chords anywhere on the neck.
Barre Chords come in 2 shapes, A and E. So, how do you know when to use the A or E chord forms? Simple. If your chord's root is on the 6th string (E), use the E chord form. If your chord's root is on the 5th string (A), use the A chord form. By A and E Chord Forms, I mean A (major), Am, A7, Asus, Amaj7 and E (major), Em, E7, Esus, Emaj7.
OK, let’s fret a F# Barre Chord. We need to know two things to do this. First, the root, F#, is on the 6th string, 2nd fret. Second, that it is a Major Chord. Think of your 1st finger as a capo. First, you fret, or "Barre", all six strings with your first finger on the root’s fret, in this case, the 2nd fret. Next you fret/finger the rest of your chord, just like an open E chord. using your 2nd, 3rd and 4th fingers. If we needed and F#7, we would put our 2nd and 3rd fingers in the same position as an E7, but at the3rd and 4th frets
OK, now let's fret a B Barre Chord. The root, B, is on the 2nd string, 2nd fret and it is a Major Chord. Barre the 2nd fret with your first finger, and use an open A chord shape on the 2nd, 3rd, and 4th strings at the 3rd fret. This takes some getting used to, especially your hand and finger strength. You will usually want you thumb pressing right in the middle of the width of the neck, directly behind your first finger.
Barre Chord Exercise I have my students start with and E major chord form at the 7th fret, then and Am chord form at the 6th fret, and so on, down to the 1st fret. So, you are alternating chord forms back and forth one fret at a time. I have found that it is much easier working from higher frets to lower frets and develops muscle memory, hand and finger strength quickly, and at the same time. [ilink-tab-1]
Here are some variations of the chord shape, such as minor, 7th, etc.