If you have properly set up both The Edge and Windows Scheduled Tasks, then your jobs will each run automatically once each week.
If something goes wrong with the automated mailing, or if you want to run an additional mailing, you can run the job again manually using the Run Now button. In this case, do not go through the Windows Scheduler because that will result in duplicate automated mailings.
In this case, go into The Edge, go to the list of scheduled postcards, and run just that batch using Run Now.
Clicking the Run Now button will not prevent the job from running as scheduled automatically as well, and might very well result in some customers receiving duplicate postcards at extra cost to you. You should only use the Run Now button if you know that the automatic job failed. For this reason, the Run Now button requires a supervisor override.