Cute way to ask her to prom?

I think candles and kisses sound great. I bet you can find a bag of tea lights at your local dollar store.

Aw, I'm excited for you!

You've got a great idea, right there, but here are some more...!
If you're familiar with her family, you could ask to go to her room. Get roses and absolutely COVER the room in them, leaving little notes tied around the stems asking her to go with you. You could get a bag of Starbursts and write "Will you go to the prom with me?" on them...one letter for each Starburst...then put them back so she has to root around the whole bag to find them and then arrange the Starbursts.
Those are my ideas...but a quick Google search yielded these...
"Make a large message with sidewalk chalk on his/her street. Draw a path and put a word about every 25 feet. Call and ask them to take a walk outside and follow the path. Use your best voice disguise."
"Take glow in the dark stars and spell out "Will you go to prom with me?" (followed with a heart and your name)."
"
Send the following note: Genesis 2:18 reminds us that" It is not good that a man should be alone...." "Would you join me for next weeks dance?"
(Courtesy of http://www.coolestdates.com/ideas_for_asking.htm)
There are all sorts of ideas...just google "ideas + ask to prom."
Best of luck!

I think that's a really cute way to ask someone. If I were in high school again and a guy asked me to prom by doing something really unique like that I'd definitely want to be his date. Have fun and good luck!