Simple.
1. Take the hair from the crown of your head and separate the rest. Put the hair that is not the crown of your head into a loose, low ponytail so it doesn't get in the way of you making your poof.
2. Take a teasing comb and tease small sections of your crown. Do the bottom hair, but never the top. If you tease/backcomb the top, it'll look really sloppy.
3. Take a small rubber band (like the ones you put on your braces) and tie the hair neatly and relatively loose.
4. Get a small jaw clip (the size will depend on how thick your hair is. Just don't use the huge ones you would use to clip back all of your hair, but don't use the teeny ones that are made for really small sized pieces of hair. I recommend the ones somewhere in between.)and pouf the now-tied hair forward. If it looks good, clip it and make sure it scrapes your scalp. Add a couple bobby pins so your hair will stay in place. If it doesn't look right, start over. For a beginner, it'll take a couple tries, but be patient. You'll get the hang of it.
5. I can't stress this point too strongly: HAIRSPRAY, HAIRSPRAY, HAIRSPRAY. You MUST have hairspray so your poof stays up and pretty for the whole day.
Glad I could help!