Its important (IMO) if you are a beginner to not use the baseball style grip yet which involves letting your tumb come up over the top of the fretboard. Rather position your thumb so that its halfway between the top of the fretboard and the bottom and lie it flat on the back of the fretboard ( you may need to tilt it slightly to one side). Curve your fingers into an arc when pressing down notes and dont lie them flat on the fretboard. Also push you hand out so that your wrist and the fretboard are on the same line. Practice playing your chords in this position and bit by bit your muscles will remember the stretches and the shapes.
Good luck and if you dont understand anything feel free to post again.