If you mean Disc's as in DVDs, have a look at > Disc Burning Quick Assist
Although note that, the Disc Burning article suggests using an External Hard Drive if you want to backup your entire system.
If you mean Disk as in External Hard Drive, there are several ways.
Simply drag and drop copy your user folders into an External Disk.
Using Time Machine > Mac Basics: Time Machine
Using Disk Utility to make a clone, see > Cloning with Disk Utility FAQ
Thank you for your prompt reply. I did mean DVD's. Since I do not have a lot of data in my computer, but it is important, I thought I could just put it all on a disk or disks to keep in case of computer malfunction. I probably should just buy an external hard drive as suggested but I will look at all the links you provided before I decide. I appreciate your help.
While DVDs work OK for small photo libraries and doc's, it is very difficult to split up and save large libraries to Disc media.
I recommend a least one or two good External Hard Drive(s).
If you require hourly backups, then use Time Machine.
If not and you only need a daily, weekly or monthly backup, then use CarbonCopyCloner or SuperDuper.