First thing you want to do is install the Excel viewer. Click on the download button and it will ask if you want to run or save. If you click on run it will start to download the viewer. After it's downloaded you should see another run command appear. Click on the second run and the viewer will be installed on your computer. Just follow the prompts until you get a confirmation that the install completed successfully.
Once the viewer is installed, you can click on the download button for the actual spreadsheet. You should be given a choice to run or save. If you click run, the spreadsheet will find the viewer and automatically open. If you click save, you can save it on your hard drive to a location you choose. The default would probably be the downloads folder in documents (from the start menu.) Keep in mind that the spreadsheet download will need some time to find the viewer and finally open.
An easy way to take a picture of your screen (sometimes called a screen shot or a snip) is to use the built in snipping tool. This tutorial for the Windows Vista operating system will also apply to Windows 7. How to use the Snipping Tool in Vista - Vista Forums
And to learn how to attach that screen shot or snip here on the Forum, give this a look: Screenshots and Files - Upload and Post in Seven Forums
BTW - welcome to the Forum!