In order to use the products, you'll need to download the zipped files and then unzip them. Your computer probably came with unzip software already loaded.
If not, there is a list of free unzip programs at TheFreeSite.com: http://www.thefreesite.com/Free_Software/Unzipping_compression_freeware/
We can't recommend any of these specifically, but it will give you a starting place.
Be sure to save the unzipped files somewhere - either on your computer, a CD, or an external hard drive so that the kits will be available to you the next time you are ready to scrapbook.
Once the kit is unzipped, open the paper or element in Photoshop or PSE by selecting File > Open, then browsing your computer for the unzipped folder. Make sure you are selecting something from the unzipped one - it usually looks like a little folder icon.
Photoshop cannot read zipped files, so it will give you a "File format not recognized" error every time until the file is unzipped.