Translation of Autohändler

I have considered the option to bring my friends from other social networks and invite them to join here. They can develop better language skills here. I'd love to pursue that goal, but I want to write in English.
My correction were added and highlighted with yellow markers and attached to this email. Tell me now if you have any questions about grammar rules, since I was a teacher 10 years ago.
Germany has a very diverse geography in the North we have the port cities of Hamburg and Bremen, and people are more open, there are a few hills up there. Then you should also visit Berlin.