Get some flowers and when you see her walk by, take them out to her. Tell her you enjoy seeing her walk by each day - she is always so pretty and happy - that you wanted to repay her with flowers. Or, if you are too shy to say that, just hand her the flowers and say that she makes you feel happy inside and you wanted to get her something. Corny, maybe, but she should love it if she likes you. After that, follow her lead.