Macro message box if Criteria is met

Having to change one of my forms to a web form have had to remove the vb coding on open event and not really any idea of how to perform the same action in a macro

Basically when the form opens in dataview which has it source to a query it checked the last record and if the row contains "warning" it shows a message box to say "Please Issue Notice"

Any ideas on how to perform the action

Thanks