The rules wizard doesn't handle dates well so you'll need to change the SQL query a little bit. Use the wizard to create a rule where Due < today (actually enter the word today to make it easy to find). You can leave the defaults on the second page of the wizard.
On the Ticket Rule Detail page look for the following line in your rule:
HD_TICKET.DUE_DATE < 'today'
You need to change this to read:
DATE(HD_TICKET.DUE_DATE) < DATE(NOW())
This will match tickets where the due date is less than today. In order to match only open tickets you need to add this line also:
AND HD_STATUS.state != "closed"
Uncheck the box to run an update query.
Check the box to add a comment to the ticket. If you are using another rule to notify the user on comments make sure that this rule will run first by value for "Order" to be less than your other rule. You could also use the function to email the user directly with this rule by checking the "Email each recipient..." box. The submitter's email will be in the SUBMITTER_EMAIL column.