I'm not a freddies employee anymore, but i cant imagine the process has changed:
1. Tell your dept. manager. If your manager isn't a total retard (well, thats saying a lot....) they should have some sort of calendar set up for you to write down your requests in advance. That way everyone can easily request days off, and everyone else can see what days are requested so theres no conflicts. If not, your manager sucks.
2. Go to a company computer. Open Session F. Login as F*employeenumber* and your overall password is your password. If you dont know your password, click on something labeled "Passport". Follow the steps and you'll reset your pasword.
3. In session F, you'll see the options. Select Time Off Request and then put in the info, and your reason why. If you have vacation time to use, you can use that under the Special Pay request. You have to do that if you want vacation pay.
The time off request in the computer is just if your manager is a dick and doesnt keep track of peoples requests, or if your schedule gets screwed around with by like the Food Manager or someone higher up who might not be smart enough to consult the dept. managers schedule to check for requests. When they load up the scheduling program you'll come up as REQUESTED when they try to slot you in.
As a dept. manager i always had a calendar, and made SURE the food manager understood when people wanted days off. I also worked at a "special" store where I wrote the schedule and the food manager just put it in the system. I've heard theres some silly eScheduling thing recently so it may have all changed, but thats how I remember it.
If you just need a random day off, my dept. manager is always good with that. We have a calendar like what Fishy said and just write on there to have that day off. The only time there's ever a problem is if a bunch of people want the same day off (like a holiday).