How do i know he ikes me?

So this guy lets call him Bob. his brother came up to me and asked me what my name was and i said my name and he was like my brother talks about you and then walked away so i had no time to ask him if it as good or bad i go to a catholic school so i can't wear any makeup or cute clothes and i am really shy the only guys i talk to are my guy friends who are nerds im not popular but not a geek and he is popular i need help should i tell him i like him or wait for him to tell me please help me