Hi nauna,

Check this example. Now please take its reference and correct your code.

HTML

<asp:GridView runat="server" ID="gvStudents"></asp:GridView><br />
<asp:Button Text="Set Role" runat="server" OnClick="OnClick" />

Code

C#

protected void OnClick(object sender, EventArgs e)
{
    System.Data.DataTable dtStudent = new System.Data.DataTable();
    dtStudent.Columns.AddRange(new System.Data.DataColumn[]
    {
        new System.Data.DataColumn("Name",typeof(string)),
        new System.Data.DataColumn("Role",typeof(string)),
        new System.Data.DataColumn("RoleValue",typeof(int))
    });

    dtStudent.Rows.Add("Student One");
    dtStudent.Rows.Add("Student Two");
    dtStudent.Rows.Add("Student Three");
    dtStudent.Rows.Add("Student Four");
    dtStudent.Rows.Add("Student Five");
    dtStudent.Rows.Add("Student Six");
    dtStudent.Rows.Add("Student Seven");
    dtStudent.Rows.Add("Student Eight");
    dtStudent.Rows.Add("Student Nine");

    List<RoleData> list = GetRoles();
    Random random = new Random();
    for (int i = 0; i < dtStudent.Rows.Count; i++)
    {
        int index = random.Next(list.Count);
        dtStudent.Rows[i]["Role"] = list[index].RoleName;
        dtStudent.Rows[i]["RoleValue"] = list[index].RoleValue;
    }

    gvStudents.DataSource = dtStudent;
    gvStudents.DataBind();
}

private static List<RoleData> GetRoles()
{
    List<RoleData> roleNames = new List<RoleData>();
    roleNames.Add(new RoleData { RoleName = "Role A", RoleValue = 52 });
    roleNames.Add(new RoleData { RoleName = "Role B", RoleValue = 65 });
    roleNames.Add(new RoleData { RoleName = "Role C", RoleValue = 29 });

    return roleNames;
}

public class RoleData
{
    public string RoleName { get; set; }
    public int RoleValue { get; set; }
}

VB.Net

Protected Sub OnClick(ByVal sender As Object, ByVal e As EventArgs)
    Dim dtStudent As Data.DataTable = New Data.DataTable()
    dtStudent.Columns.AddRange(New Data.DataColumn() {
                                New Data.DataColumn("Name", GetType(String)),
                                New Data.DataColumn("Role", GetType(String)),
                                New Data.DataColumn("RoleValue", GetType(Integer))})
    dtStudent.Rows.Add("Student One")
    dtStudent.Rows.Add("Student Two")
    dtStudent.Rows.Add("Student Three")
    dtStudent.Rows.Add("Student Four")
    dtStudent.Rows.Add("Student Five")
    dtStudent.Rows.Add("Student Six")
    dtStudent.Rows.Add("Student Seven")
    dtStudent.Rows.Add("Student Eight")
    dtStudent.Rows.Add("Student Nine")
    Dim list As List(Of RoleData) = GetRoles()
    Dim random As Random = New Random()
    For i As Integer = 0 To dtStudent.Rows.Count - 1
        Dim index As Integer = random.[Next](list.Count)
        dtStudent.Rows(i)("Role") = list(index).RoleName
        dtStudent.Rows(i)("RoleValue") = list(index).RoleValue
    Next
    gvStudents.DataSource = dtStudent
    gvStudents.DataBind()
End Sub

Private Shared Function GetRoles() As List(Of RoleData)
    Dim roleNames As List(Of RoleData) = New List(Of RoleData)()
    roleNames.Add(New RoleData With {.RoleName = "Role A", .RoleValue = 52})
    roleNames.Add(New RoleData With {.RoleName = "Role B", .RoleValue = 65})
    roleNames.Add(New RoleData With {.RoleName = "Role C", .RoleValue = 29})
    Return roleNames
End Function

Public Class RoleData
    Public Property RoleName As String
    Public Property RoleValue As Integer
End Class

Screenshot