How do I get my fingers to stretch?
Chords like C & F that stretch over 3 frets can be difficult at the beginning. Part of the problem is that we use our weaker hand to make the chords and this takes time to get stronger and for the muscles to stretch. Try placing the third finger into position first for these chords. If it is really proving difficult then it might be an idea to look for a smaller guitar as the frets would be a little bit closer together. You could also try using a capo on the 3rd or 4th fret, this will move your hand into a position where the frets are closer together and make it easier to stretch those fingers. After a few weeks you can try moving the capo back a fret to see if the fingers can now stretch that bit further and over time keep moving the capo back until you are able to play without it.
Every time you position your fingers to play a chord you should be trying to get them just beside the fret as close as is possible. The last part of the previous sentence is important because in some chord shapes it is just not possible to get all the fingers right beside the fret without contorting your hand. You cannot sacrifice the other conditions of finger placement just to stretch to the fret. So you must use your fingertips, have the first knuckle bent, do not let your first finger touch the neck and keep your wrist reasonably straight. This all might seem like an impossible task at first with the C chord but it should in time, with practice, be possible to get all three fingers right beside their respective frets. This should be a conscious part of your practice routine until it is no longer something you need to worry about. Remember don’t hurt your hand trying to get this in your first attempt, stretching muscles will take time, be prepared to give it the time it needs.