Hi Gail,
If you want to go cheap & easy and just get it over with, you could drive your PC to an Autozone. They will match up your batteries (assuming they have replacements in stock), install the new batteries, and dispose of your old batteries. Installation is free. I am not sure of disposal, but I think that is also free. Autozone offers fairly reasonable prices and the free installation.
Walmart auto centers might also offer the same services.
BUT..........
If you are particular as most of us here have become, you will want to do some research.
As for me, I got tired of dealing with battery trouble and seemed to have come up with a good resolve
HERE. Being only 2 years to-date, the jury is still out, but so far it has been very promising.