code required for adding 2 columns in gridview

Partial Class Default2

    Inherits System.Web.UI.Page

    'Declare two dataset on page level

    Private dsUserVendorName As DataSet

    Private dsUserRoleName As DataSet

    Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load

        'Call following both function here

        LoadUserVendorName()

        LoadUserRoleName()

    End Sub

    Private Sub LoadUserVendorName()

        'Open Connection

        'Fill whole usersId and associate vendor name in dsUserVendorName dataset

    End Sub

    Private Sub LoadUserRoleName()

        'Open Connection

        'Fill whole usersId and Role name in dsUserRoleName dataset

    End Sub

    'This function call from grid view

    Private Function DisplayVendorName(ByVal intUserId As Integer) As String

        Dim strVendorName As String

        ' find Venodor Name from dsUserVendorName dataset using intUserId

        Return strVendorName

    End Function

    'This function call from grid view

    Private Function DisplayRoleName(ByVal intUserId As Integer) As String

        Dim strRoleName As String

        ' find Role Name from dsUserRoleName dataset using intUserId

        Return strRoleName

    End Function

End Class

Can you tell me what i can write in Function DisplayRoleName(ByVal intUserId As Integer).Already the gridview is existing and want to add 2 new columns in the existing gridview.urgent..