Here’s a highly recommended program for backing up your data.
Cobian Backup. It’s FREE !
I do a data backup once a week and about once a month I help people who don’t backup their data and are trying to recover a file. Don’t be one of those.
I also recommend that after backing up to an external hard drive, that you disconnect it from your computer and unplug it from any electrical sources. While it’s tempting to just keep it plugged in at all times, if you have an electrical surge, it might fry both your computer’s hard drive and your backup.