Depends on many factors including what backup medium you had in mind.
Quick and dirty backup:
1. Search this forum for "Forcing Database to Close" and similar word combinations to that effect. You don't want the database to be open when you do the backup.
I recommend the method that uses a startup form that never goes away (but just minimizes and hides itself). Once per minute, 5-minutes, whatever, have it wake up and see if it is within a couple of time increments of the backup start time. If so, have it QUIT the application. But you might see another way that appeals to you more when you do the recommended search of this forum. Pick the way that makes sense to YOU.
2. Put something in your Windows Task Scheduler that runs at a time when no one should be in your database. If all you are doing is making a disk to disk copy of the file, you can write a little .BAT file to do a couple of things.
2.1 Find the intended backup directory. Delete the oldest copy of the file in question. (See 2.2 below.)
2.2 Rename the next oldest copy to become the oldest copy. Ripple through as many copies as you are keeping. The last step is to rename the youngest copy to be the name set aside for the second-youngest copy.
For instance, db.bak, db.bk2, db.bk3, ... db.bk9 - gives you 9 copies of the original, each with identifiable names that tell you the order in which they were copied. The .BAK is youngest, the .BK9 is oldest.
2.3 Copy the "live" database to the name/place selected as the youngest copy. That's it, you are done - if this is the simplest case.
Now, if you have a tape drive or some other medium - say, CD-WORM or DVD in some flavor or another - you need to have an operator present to load the proper media at the right time and to later file it away. In this case, if you are going to have an operator on board anyway, look into either the Legato or ARCServe packages. We've used both on our systems with a reasonable level of success.
Even though you have an operator present, the backup job can be predefined so that all you do is load media, click on a button, and wait until it tells you it is done. Single-user licenses for either package probably cost no more than a small body part. Maybe not even as much as your firstborn child.
A couple of last thoughts.
1. It matters less the exact package and method that you use than that you use any method regularly. I.e. buy the nicest car in the world. If you don't drive it, why did you bother? A cheap rust-bucket can sit in the garage as well as a spiffy new roadster. In the realty industry, the slogan is Location, Location, Location. In the data recovery business, it is Backup, Backup, Backup. There is NO SUBSTITUTE for regular repetition of backups.
2. Once you have a quite moment, TEST the ability to recover the data from your chosen backup medium. Obviously, if you are using the disk-to-disk method you will have less trouble than if you are using tape or CD media. If you cannot recover, you weren't doing a backup, were you? Test BEFORE you need it. You won't get the chance to fix it after-the-fact.
3. If media isn't local-disk to local-disk on the same site: Some folks have friends at other sites with whom they can make arrangements for off-site media storage. I.e. you buy a storage cabinet big enough to hold 100 of your media. But you only planned to keep 50 copies. See if you have a friend who just did the same thing. Then make extra copies of your media and put them in your friend's cabinet. Let him/her make extra copies of his/her media and store them in your cabinet. Then each of you has an on-site and an off-site copy in case of disaster. You can retire the oldest media when you bring over the next bunch of newly recorded media. And you can even take turns being the "designated driver" who brings media to the other site.
Trust me... all it takes is one good fire or storm to make that off-site media become worth its weight in platinum. I'm from New Orleans. We had tapes in a sister site in Texas. Hurricane Katrina killed our building and our local tape copies. But we never lost a transaction - because we had an alternate storage site for our copies of the primary backup tapes.