Well, I had two years of Cosmetology in high school and I am going to try to explain this the best I can.

To get the "poof" buy some volumizing hairspray. Big Sexy Hair is good but a little pricey. Charles Worthington makes some exclusive to Walgreens and it is just as good for only about $3-4. Comb your hair upwards and spray the hairspray at the roots, then comb the hairspray through to the ends. Take a good pick or comb, and begin teasing at the roots. Then pick up another section and do the same, until it's poofy and you have the desired amount of hair you want to pin up.

Next, get some bobby pins that are either sparkly or you can get some to match your haircolor. Take a comb, and smooth out just the roots, and pin up each section until you have the desired amount pinned up.

Finish, with a good spray of the hairspray.

I hope this works for you, I tried to explain it the best way I could. =)