Stressed about a lot of things

I agree…this sounds like depression…go immediately to the counseling center.

After that, check out ideas on making friends:

http://talk.collegeconfidential.com/college-life/1808143-having-trouble-adjusting-to-college-making-friends-top-10-things-to-do.html

Ideas on doing well in classes:
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http://talk.collegeconfidential.com/college-life/1920853-college-is-a-step-up-from-hs-16-tips-on-doing-well-in-college.html