Send email reminder if a task is not complete

I know other people already asked this questions, but I could not figure out how to do it. It would be a big help for me if it is step by step…

In my task list, I have a “Project log-in” and a “Due Date” columns. I would like to create a WF that could send a reminder email to the Assignees 7 day prior to the due date. How would I do this?

Thank you, Dennis