If you are having trouble opening Excel files because you do not have Excel, you can download a free program called Open Office which can open Excel files. Depending on which type of computer you are using, choose one of the links below:
The other possibility is to right-click on the Excel file and say "Open with...". There may be another program on your computer which can open the file. Recent versions of Internet Explorer can view Excel spreadsheets but cannot modify them or produce graphs.