how to make textbox equal the checked value of the listview

Hi Experts,

How can I make textbox1.text equal the checked value(s) of Listview1?  The ListView contains (2) columns;

Offense ID                Offense Description
     1                                DWLSR
     2                             Grand Theft

I need textbox1.text to read as "1,2" if both are clicked.

Below is the code that I currently have, thanks in advance for you cooperation.

        Dim conn2 As New System.Data.SqlClient.SqlConnection("Persist Security Info=True;Server=xxx.xxx.xxx.xxx;Database=Reporting;uid=uid;network=dbmssocn;password=password")
        Dim da2 As New System.Data.SqlClient.SqlDataAdapter("Select * from tblOffense", conn2)
        Dim ds2 As New System.Data.DataSet
        Dim cmd As New System.Data.SqlClient.SqlCommand("Select offense_number, offensedesc from tblOffense where incident_ID='" & IncidentPeopleAdd.Incident_ID.Text & "' and ARN='" & IncidentPeopleAdd.ARN.Text & "'", conn2)


        Try
            conn2.Open()
            Dim myReader As SqlDataReader = cmd.ExecuteReader()
            Do While myReader.Read()

                Dim lvi As New ListViewItem(myReader.Item("offense_number").ToString)
                lvi.SubItems.Add(myReader.Item("offensedesc").ToString())
                ListView1.Items.Add(lvi)



            Loop
            myReader.Close()

        Catch ex As Exception
            MessageBox.Show(ex.Message)
        Finally
            conn2.Close()
        End Try