these chords are called barre chords. to play them, you have to flatten the first finger over all 6 strings. you'll notice that the shape for an F#m chord is very similar to an E major chord.
Emaj F#maj Amaj
E 0-----2-----5-----|
B 0-----2-----5-----|
G 1-----3-----6-----|
D 2-----4-----7-----|
A 2-----4-----7-----|
E 0-----2-----5-----|
This is because they are the same 6 notes, just moved up two frets. you can't have open strings moved up two frets without fretting them, so your first finger kinda becomes a new nut. i've also drawn an alternative version of Amaj as well. These barre chords, with their root on the 6th string are often known as "E-shaped", because the shape of the major chord is the same as the open E major chord. You can use variations of E chords, such as suspensions and 7ths, etc to create other E shaped barre chords, and move them up and down the neck.
Once you can play chords like F#maj, then its very easy to play Bm. It is just the same shape moved up by one string. B major is loads harder to play. You can either use your 3rd finger to barre across the 4th fret, use fingers 2 3 and 4 to fret the 4th fret, or miss out the D string and mute it with your first finger, which is a good way out at first, but its useful to be able to play the other way!
F#maj Bm Bmaj
E 2-----2-----|2-----2-----|
B 2-----3-----|4-----4-----|
G 3-----4-----|4-----4-----|
D 4-----4-----|4-----x-----|
A 4-----2-----|2-----2-----|
E 2-----x-----|x-----x-----|
As for Cmaj7 and Dsus2 and Dsus4, they can be played using open strings.
Cmaj7 Dsus2 Dsus4
E 0-----0-----3-----|
B 0-----3-----3-----|
G 0-----2-----2-----|
D 2-----0-----0-----|
A 3-----x-----x-----|
E x-----x-----x-----|
Barre chords are really hard to play at first. It takes quite a while to get the strength between your thumb and first finger. When you learn to play barre chords, try fretting the 8th fret with your first finger and nothing else. Then pick every string individually, and make sure that each note is clear with no buzzing or muting. Then you can add in the rest of your fingers. It takes a while to get your fingers to remember the shape, but when you've got it, its like learning 12 new chords instead of one.
hope this helps.