It sounds to me that she would like a casual really fun date. You might take her some flowers(not red roses/or carnations) but maybe something like daisies, or something bright and colorful. Find out what she enjoys doing and do it. Get a friend to go with you so it's a double date. You need to take a shower, wear deodorant, and wear clean clothes.
Some of the best dates I've been on include dates that are really well planned out or include romantic surprises. Like horse drawn carriages, nature walks, seeing something beautiful(like a sunset). Going someplace fun for lunch/dinner good food,( well lit, and interesting) Don't expect anything physical on a first date it's not likely to happen especially with two other people around. Don't try to get her alone that can come off as creepy instead make sure you are nice to the other "couple" Ask at least 5-7 questions about her and each of the other people(even if they are boring and the other couple are stupid too) but make sure they are appropriate and flow with the conversation(I frequently mess this up too but you should try)
Be sure to compliment her. Your clothes look nice, your hair looks nice, or some such....most women like that. Make sure you don't end up paired up with her friend on accident....Also be sure to ask if she would like to see you again at the end of the date and figure out something SHE would like to do to invite her to(casual and in public). This makes you look considerate.