Look at Alex Reynolds answer on here 
UITableView - change section header color
    - (UIView *) tableView:(UITableView *)tableView viewForHeaderInSection:(NSInteger)section 
    {
      UIView *headerView = [[[UIView alloc] initWithFrame:CGRectMake(0, 0, tableView.bounds.size.width, 30)] autorelease];
      if (section == integerRepresentingYourSectionOfInterest)
         [headerView setBackgroundColor:[UIColor redColor]];
      else 
         [headerView setBackgroundColor:[UIColor clearColor]];
 return headerView;
}
If you  just get a background color but no text
Look DoctorG answer on same question
       UILabel *label = [[[UILabel alloc] initWithFrame:CGRectMake(10, 3, tableView.bounds.size.width - 10, 18)] autorelease];
    label.text = @"Section Header Text Here";
    label.textColor = [UIColor colorWithRed:1.0 green:1.0 blue:1.0 alpha:0.75];
label.backgroundColor = [UIColor clearColor];
[headerView addSubview:label];