Girl problem at school (rephrased)?

im in middle school in the 7th grade, and during lunch a few days ago, i saw this girl, and i don't know her, i was gonna try and talk to her and stuff, but my stupid friend saw it, and he talked to her after lunch (FOR ME) and i didn't know he was, and asked her out and i didn't want him to, but she said yes so its not all bad, but i don't know her name and i want to get to know her, and talk to her, but she already likes me enough to want to go out, so what do i do know, and shes in 8th grade, but shes 13 or 14 and im almost 14, so its not much of an age difference.