How To Write Code For A Report

I have a report rptEnvelopes to print envelopes. In the report I have text box called txtRecipientName .
I have a qryAddress with fields notNo, IDCard, Fname, Lname where notNo is a field that takes its value from a combo box called cboSelectEnvelope from a form frmPrinting. I then wrote the following code:

Private Sub Report_Open(Cancel As Integer)

Dim dbLet As Database
Dim rsLet As Recordset
Dim sqlLet, criteriaLet, txtRecipientName As String
Dim stLet as String

Set dbLet = CurrentDb
sqlLet = " Select DISTINCT IDCard FROM qryAddress " & _
"WHERE notNo = " & Forms!frmPrinting!cboSelectEnvelope
Set rsLet = dbLet.OpenRecordset(sqlLet, dbOpenSnapshot)
If Not rsLet.EOF Then
rsLet.MoveLast
stLet = "rptEnvelope"
criteriaLet = "notNo=" & Forms!frmPrinting!cboSelectEnvelopeReports
'This is where I go wrong:
'How to I declare txtRecipientName, on rptEnvelope, to get the value rsLet!Fname&" "& rsLet!Lname
DoCmd.OpenReport stLet, acViewPreview, , criteriaLet
End If
rsLet.CLOSE

NOTE: Private Sub Report_Open is called from the On Open Event of rptEnvelope