I have a form to be completed by staff ONLY if they have approval to proceed
with the work. I've managed (with this group's assistance!) to have a
message box pop up but I want to add a wrinkle where if they press "yes",
they can proceed to fill in the form, if they press "no", the file closes.
I've never done If/Then in VBA (this is actually my first foray into VBA).
Help please!:

Sub Auto_open()
MsgBox "The Project Manager's or Project Administrator's approval must be
obtained prior to proceeding with this work. Has approval been obtained?.",
vbYesNo, "WARNING"
End Sub