Combine Two DataTables Into One Datatable

How to combine two datatables into single datatable - C# 

public void getgroupRecentActivity()

        {

            DataTable dtjoingroup =   Group.GetAllGroupDetailbydate(Request.QueryString["GroupID"]);

            DataTable dtcreateGroupForum = Group.GetAllGroupForumDetailbydate(Request.QueryString["GroupID"]);

            DataSet dsjoin1 = new DataSet();

            DataSet dsjoin2 = new DataSet();        

            foreach (DataRow dr in dtjoingroup.Rows)

            {

                dr["GroupName"] = "commented on the forum";

                dr.AcceptChanges();

            }

            foreach (DataRow dr1 in dtcreateGroupForum.Rows)

            {

                dr1["GroupName"] = "joined the Group";

                dr1.AcceptChanges();

            }

            dsjoin1.Tables.Add(dtjoingroup);

            dsjoin2.Tables.Add(dtcreateGroupForum);

            dsjoin1.Merge(dsjoin2);

           

            DataTable dtrecentActivity = dsjoin1.Tables[0];

            dtrecentActivity.DefaultView.Sort = "date desc";

            dtrecentActivity.AcceptChanges();

            DataView dv = new DataView(dtrecentActivity);

            dv.Sort = "date desc";

            dtRecentActivity = dv.ToTable("dtrecentActivity");

            //dtRecentActivity = dtrecentActivity;

            dtRecentActivity.AcceptChanges();

            //GridView1.DataSource = dtRecentActivity;

            //GridView1.DataBind();

            //DataView dv = new DataView(dtrecentActivity);

            //dv.Sort = "date desc";

            //DataTable dtrecentActivityNew = dv.Table;

       

        }