Hello,
"How to create a workflow, which should run a background job where it has to monitor custom table for every 5mins and i have to send mails(to different level) using deadline monitoring?"
What is in this custom table, why does it need to be monitored every 5 minutes and what is in these proposed emails?
If you want emails sent every time a particular change happens in the table then you could use SWEC to create an event (which starts the workflow) instead of doing constant monitoring.
regards
Rick Bakker