When I was 19, I celebrated my first Valentine's Day while being in a relationship. I was so excited, but didn't know what the rules were. What should I get him, or was I even supposed to get him something?

When I was 19, I celebrated my first Valentine's Day while being in a relationship. I was so excited, but didn't know what the rules were. What should I get him, or was I even supposed to get him something?