Help me please

So my sister would always talk about this guy that she liked. And I never knew who he was. Then I transferred to the school that she went to and I saw some guy who was cute so I started crushing in him then like two days later, she showed me who he was and he was the guy who I liked and thought was cute. I don't know what to do anymore I like him but she doesn't know what should I do? 😭😭