I'm going to make a few assumptions here. First assumption, that your frmStartup is a modal dialog. If so, you can grab properties from the form from your Sub Main. Something like this (please remember that I'm using a C#-to-VB converter so the syntax may be off a bit):

If frmStartup.ShowDialog() = DialogResult.OK Then
   Me.MyVariable = frmStartup.FormVariable
End If

and then pass it to your frmMain like this:

Dim oMainForm As New frmMain(Me.MyVariable)
oMainForm.Show()

of course, frmMain would need to declare parameters in it's constructor, like this:

Public Class frmMain
   Inherits System.Windows.Form
   
   ' Form's constructor
   Public Sub New(MyParm As String)
      ' code here to handle parm
      InitializeComponent()
   End Sub 'New
End Class 'frmMain

Anyway, that should be enough to get you started ...

~~Bonnie