You says that you cannot get used to the life in US and don't have any friends there.Therefore,I would like to give you some advice.
First and formost,you need to learn their life habits and show your respect to the local costoms.Second,good communication with your american classmates can help you integrate into them better.Third,you can participate in more outdoor activities,so that you can make more friends.Last but not least,do pay attention to your manners when communicate to others.
Those are my advice,I believe you could do much better!
