How to ask a girl out ?

i'm goint o a dance tomorrow and the grl i like is gonna be there. i'm gong to ask her out but i don't know ow to do it without all of her friends. if she says no , than they'll laugh at me for the rest of the night , but i don't think she'll say no . :D . how can i appeal like more dreamy or romantic to er ? i want to show her how i really feel about hr.basically , how can i ask her out without making an *** out of myself ?? <3