How to Sew on a Button

Thread your needle and tie a knot at the end of the thread.
Position the button on the fabric. Line the button up with the other buttons on the garment.
Push the threaded needle up through the fabric and through one hole in the button. Pull the thread all the way up.
Place a pin across the center of the button and hold it there until the next stitch helps keep it in place. When the pin is withdrawn later, it will allow the slack necessary to create a "shank" so that there will be space between behind the button for the material that will need to go there when the garment is buttoned.
Push the needle down through the next hole and through the fabric. On a 4-hole button choose the one diagonal to the first hole if you want the threads to cross in an "X" formation. If you want two parallel lines of thread showing, choose the next hole that is opposite the first. Still holding the pin in place, pull the thread all the way through. Once that is done, the pin will be kept in place by the thread.
Bring the needle up through the first hole (for a 2-hole button) or a new hole (for a 4-hole button) and pull the thread all the way through the fabric.
Repeat the sewing process enough times to make sure the button is securely in place. On 4-hole buttons, make sure that the stitches have been made evenly, so that all four holes are equally used.
On the last stitch, push the needle through the material, but not through a hole in the button. Pull the thread out into the area between button and material, remove the pin and pull up the button a little. Twist the thread six times around the thread between between the button and the material to reinforce the shank you have created. Then push the needle back down through the material.
Tie a knot underneath. Then make another knot for extra secureness and cut off excess thread.