How does it work when you're riding a bus long distance?

So I'm planning on going on a trip to New York City to see my friends and family for a couple of days. I want to take the bus there by myself (thats my only option right now). I'm 17 years old and I have never rode on a bus myself going long distance. Like how does it work? How do I get tickets? When I get to the bus station where do I go? How will I know which bus is the right one to go on? I'm leaving from Richmond, VA to New York so I need to know these things before I go.