I have been able to sort this one thank you

Code:
Private Sub Workbook_Open()
On Error GoTo myErrorHandler:

Dim User_Name As String
Dim myRange As Range
Dim yesNo As Variant

Set myRange = Sheet2.Range("A:A")

User_Name = Environ("username")

yesNo = Application.WorksheetFunction.VLookup(User_Name, myRange, 1, False)

myErrorHandler:
    If Err.Number = 1004 Then
        UserForm2.Show
    Else
        UserForm1.Show
    End If
End Sub