A hair weave is a way of affixing hair that's not yours--typically from a human donor--to your own natural hair in such a way that the two are indistinguishable. To add a hair weave, you must first create a flat, stable surface in your own hair, which the weave will then be stitched to. This is where the rubber bands come in: They help create a flat, bump-free surface. Ideally, you should have a friend help you with this process. It should take less than an hour.
Shampoo and moisturize your hair before beginning your rubber-band hair weave. Let it dry.
Comb the hair out so it's tangle-free. Make a horizontal part on the back of your head, just above the level where you want the hair weave to sit. Tie or pin the hair above this part on top of your head, out of the way.
Separate the hair below the part into small segments, each about the width of your smallest finger, and rubber-band each segment into a tiny ponytail.
Start from the right side of your head and rubber-band the first two tiny ponytails together. Then pair up the next two, then the next two, rubber-banding them together in pairs all the way across the part you made.
Do one more line of rubber-banding. Starting from the left this time, rubber-band the tiny ponytails together in pairs, below the previous rubber-banding, all the way across to the right.
Place the weft--the band or strip that holds together the hair weave you're about to apply--across the part you made, as close to your scalp as possible.
Fold a long piece of thread in half and thread the separate ends through the eye of a blunt needle.
Run the needle down through the hole between two tiny ponytails, as close to your scalp as possible, starting on the far right side of your head. Don't pull the thread all the way through.
Bring the needle up on the other side of the weft by passing it through a hole in the second layer of ponytails you made. Then pass the needle through the loop in the end of the thread and pull it taut.
Work from right to left, essentially wrapping the weft to the hair by passing the needle around the weft between tiny ponytails.
Work all the way to the end of the weave on the left, tie a knot in the thread to fix it in place, and clip the extra.
Let down the hair that you pinned on top of your head. The weave should now be indistinguishable from your natural hair.