Reply to Need help at flight booking (from Germany to USA, Minnesota)

Hello DJTT, this is kind of a stupid topic for a dj community , and I am sorry for that, but I hope you can help me:
I wanna visit my cousins for 2-3 weeks in Minnesota, got a letter of agreement (im underaged) but have no experience with this stuff, same goes to my parents. What do I have to look out for? It's my first time visiting the USA. I got a german citizenship. Any good sightseeing there? Places I should have seen? Shouldn't be too far. I hope some people can help me.