As per my understanding you want to merge two column values from two different DataTables into a single DataTable.

In a simplest manner you can iterate through each row of the two DataTables to be merged and then save merged values into a result DataTables

Please have a look at the sample code below, in case you have any problem, please let me know.

        //Inserting value in the first DataTable dt1

        DataTable dt1 = new DataTable();
        dt1.Columns.Add("FirstName");

        DataRow dr = dt1.NewRow();
        dr["FirstName"] = "FirstName_1";
        dt1.Rows.Add(dr);

        dr = dt1.NewRow();
        dr["FirstName"] = "FirstName_2";
        dt1.Rows.Add(dr);

        //Inserting value in the second DataTable dt2

        DataTable dt2 = new DataTable();
        dt2.Columns.Add("LastName");

        DataRow dr1 = dt2.NewRow();
        dr1["LastName"] = "LastName_1";
        dt2.Rows.Add(dr1);

        dr1 = dt2.NewRow();
        dr1["LastName"] = "LastName_2";
        dt2.Rows.Add(dr1);

        //Merging the values of two columns into another DataTable dt3

        DataTable dt3 = new DataTable();
        dt3.Columns.Add("Name");

        DataRow dr3;
        for (int i = 0; i < dt1.Rows.Count; i++)
        {
            dr3 = dt3.NewRow();
            dr3["Name"] = dt1.Rows[i]["FirstName"].ToString() + " " + dt2.Rows[i]
            ["LastName"].ToString();
            dt3.Rows.InsertAt(dr3, i);

        }