VB 2005
1) From All Windows Forms
drag HelpProvider control and drop it on your form
The control will appear on a "status bar" beneath the form

2) Set the properties of HelpProvider1
HelpNameSpace (the name and full path to the CHM document)
Set Modifiers to public

3) Set properties of the form
HelpNavigator on HelpProvider1 = TableOfContents

Now,when the user presses F1, help will launch

To launch help from a button (or a menu selection) add the following to your app.
    Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
        SendKeys.Send("{F1}")
    End Sub