This is generally considered an advanced position. It is only to be used with very cooperative, older children (usually at least 12 mos.). For this position, you may also want to start with the rings behind your shoulder. Then when you finish adjusting, the rings will be in the right place. However, you can also start with the rings in the normal position and end up with the rings closer to your navel or hip. Just make sure the rings do not sit on one of your breasts, if you're a nursing mother. Place the child in a hip carry and swing him/her behind your arm. Lean forward so that your back is almost horizontal with the ground and adjust your child so he/she is lying on your back. Make sure to reach back with one arm and keep your child steady. While you are still bent over, pull on the tail to adjust and tighten the sling around them. The bottom edge of the fabric should, again, hit behind their knees and his/her bottom should be lower than their knees & be nice & snug. Also, in this position, the top edge of the sling should come up high under your child's armpits. This is high enough to keep your child snug but keeping the arms out is an extra safeguard in case he/she starts to slip. The sling will catch under their arms and keep him/her up.
If you are a nursing mother and you are carrying your child in the Backpack position, make sure that the edge of the sling fabric is not pressing on your breast tissue. You can either make the top edge of the fabric spread across your body or hit above your breast tissue, or you can push it down so that it is below your breast.

*It is important that you have another person with you the first few times you try the back carry position. That person should check the position of your child and help you with any adjustments, if needed. When your child is in the rear carry position, always be aware of your environment and the position and behavior of your child.*