You'll need a third party app, such as GoodReader, to be able to open that WinZip file. Then you'll need another third party app to be able to modify or edit the Excel file that was contained in it. Apple's Numbers app is a good program for processing Excel files.
Good to hear from you. You’ll find a whole bunch of iPad enthusiasts in this Forum who are only too willing to help other iPad owners and to hear of their experiences. Don’t be afraid to post any questions you may have or use the ‘Search’ button near the top of the Forum web page. I usually find I discover one new interesting and useful piece of information about my iPad every day - and often not even what I was looking for!!
Hope to hear from you soon with your thoughts about the iPad.
Have fun and enjoy your iPad
If you don’t already have it you can download a copy of the iPad manual for free.