In Windows Vista or 7 search "task"; Task Scheduler should be at the top of the list. Open it. Click "create basic task". Type in the name you want to call it and a description if you like. Specify when you want it to start. Specify date, time, and recurrence. Choose an action (start a program). Browse for the batch file. At the end, view over it to make sure it is exactly what you want, and click finish. At the task manager main menu, you will have to refresh the list at the bottom for your new batch file to appear (this is optional, it will take affect either way). It is best for the computer to restart to take affect.
Windows XP users and older with have a slightly different process. See next step.