update field in database using dataset

I am trying to update a field in the database using datasets.  The acceptchanges() doesnt seem to be working like i thought it would.  How do i accomplish the update?

The code is below:

DataSet CHEnroll= new DataSet();

switch(ddlFileFormat.SelectedIndex)
{
      case 0:       //Enrollment
      CHEnroll = GetVEnroll(strCardHolderStatus);
      break;
                                :
                                :
}            

DataRow vEnroll = CHEnroll.Tables[0].Rows[0];  //rstCardHolder

if (CHEnroll.Tables[0].Rows.Count>0)
{
      foreach (DataRow ch in CHEnroll.Tables[0].Rows)
      {
            ch["CardHolderStatus"]="EnrollPending";
            ch.AcceptChanges();
                 }
}