there are many ways to play a B major chord. one tis to play it like a Barre chord. in which you use your first finger to play the root note (5th string 2nd fret) and your third finger to play the other 3 notes by 'Barring' them across the 4th 3rd and 2nd strings at the 4th fret. you will miss the high note F# on the 1st string. its not really right but it might work for now.
another thing that will take a while is to start doing finger streching trills, which is a rapid series of hammer on and pull offs. start with your 1st fing on the 3rd string and the 3rd fret, pick the note then hammer on your 2nd finger to the 4 th fret and pull off, keep doing that rapidly, then keep your 1st finger on the 3 fret and hammer on with your 2nd finger on the 5th fret. ii think you should have the idea by now. do this with all your fingers reaching as far as you can without hurting yourself. if you fell any pain other than the usual muscle soreness stop.
do that every day as part of your practice warmup and in a few weeks or or you should see an improvment in your reach. also move around the neck and strings with it.
if you have any questions just ask some one will help you out.
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