Girl help! or guy idc.?

ok well there this girl at my school she is a grade lower than me. i think she likes me because she keep looking at me. well im not sure if i like her but idc and im not ready for a relationship or interest. we never talked before but how do u tell to someone u dont know. because i dont want her to feel bad when i say noooooo! and i dont want her wasting her time on me. known her since 2 years ago.