I want to make a backup

Why backup? The philosophy of backups.

What do I use to make a backup?

You need a CD burner.  You can bet that for the next five years or more just about every personal computer will be able to at least read a CD.  You can't say the same for floppies or zip drives.  Many new computers do not come with floppy drives.  And the question of ubiquitous zip drives have always been, well, questionable.  Bottom line, if you can't burn a CD, you need to get the hardware and learn how.  

Check the sales at office supply stores near you.  Often, most notably after Christmas, there will be  huge sales on CD Burners and CDs.  These sales usually take the form of a rebate. 

For example: You buy the burner for $40.  You send in the box top or purchase code you cut from the box.  You wait 3 to 8 weeks for your $40 rebate. 

Same thing applies to CDs.  I just have one bit of advice.  Make up an email alias.  Most ISPs will allow you several mailboxes.  Use one for rebates.  Do not provide your phone number, just provide an email address you plan to dump after you receive your rebate.  Because the folks who give you that rebate will sell that email address to spammers.  Get the money, dump the address and dump the spammers.

Save What?

First, save everything in My Documents.  For you and any other user of your computer.  Most programs save files to My Documents. 

Run the programs you use: Quicken, Quickbooks, Tax Programs (TurboTax, TaxCut, etc).  Click on File Save As and see where they try to place your file.