We have set up a weekly note with his teacher, who does not seem real fond of our son. We grounded Josh from playing football with his friends, and took away things he loves to do, but we are at a loss on how to help him behave.
Talk with the teacher about working with you to focus on the positive with you son. Weekly notes don't work well with first-graders, who need more immediate reinforcement for their behavior. Ask the teacher to send you daily notes, explaining that you don't need anything elaborate; something as simple as a "smiley" or "frowny" face or checkmark/check plus/check minus will let you know how his day was. Follow up at home with rewards for good behavior.
Talk with the school counselor as well. He or she may be able to give Josh some individual time or involve him in a small group on good behavior. The school counselor may also help support Josh's good behavior at school.