
Start by finding the center of your wrap. I do this by just folding it in half.
I then hold onto the center fold with my fingers.

Hold the center fold with your left hand. Pull top fabric rail (edge) through your right hand until you have your arm outstretched beside you.

Now, wrap the right arm around your head, so the fabric drapes around your back and over your left shoulder. (This should prevent the fabric from twisting as you wrap it around your back.)
Now tuck the end of the fabric behind the center point, still being held by your left hand. Fabric should feel smooth across your back.
Switch hands holding the center point of the fabric.
Pull the top fabric rail through your left hand until your left arm is outstretched.
Wrap your left arm around your head, as you did your right, before. Again, this prevents the fabric from getting twisted in the back.
Drape the fabric over your right shoulder.
Feed this end of the fabric, down behind the center point of the fabric.
This will leave both ends tucked in close to your body between you and the center point.
Now, cross the two pieces of fabric, by holding the top rails (edges) of the fabric.
Pull your arms around behind you, with the fabric.
So, now you have a cross, across your chest, and a band of fabric in front of it.
I tie the fabric in a not, some people choose to just tuck the ends. If the fabric is long enough, I sometimes wrap it around again to the front and tie there, so I don't have knot in my lower back.

I like to pull the two edges, that cross in front, out a little. (It's okay if the fabric feels tight, it will give, and there will be room for you itty bitty.) :-)
Now, pick up your little one. Dipsy has volunteered to help me here, since my Darling Daughter is now two. (Your itty bitty will ride lower on you, since he/she weighs more than Dipsy.)
For newborns, we just slide them into the inside cross of fabric. Be sure it is spread out, all the way across their little bum.
For older children, when you put them in, make sure the fabric reaches from the back of one knee to the back of the other knee. (I'll put in some other photos of this, later.)
Next, you pull the second, outside, fabric cross, across the baby's back. Again, make sure the fabric stretches across the entire bum of the baby.
With older babies, again, the fabric should stretch from the back of one knee to the back of the other knee.
As a final safety precaution, I pull the band (the center-point) of the fabric up over the baby's back, leaving some of it under the baby to help him/her feel snug.
A little bounce will help baby to settle down into the wrap.
Make sure baby can breathe, and that his/her little face isn't wedged between the mammaries. :-)
And that's how it's done. I took a lot of photos to help you see how I wrap the fabric around my back. I will now attempt to make a snapshot video for you to watch me do it too. :-)
Good Luck & God Bless!