How to know if a boy likes you?

I am a college student (21Female) as well as doing coaching for government jobs. One day in coaching I saw a guy (same age of mine)of whom I don't even know the name but I think I started liking him to some extent. One day he also noticed me and since then sometimes during the entry and sometimes while exiting our eyes meet. I want to talk to him so badly, but I am a girl so I hesitate and do not know how to start the conversation. What should do I do?