Ok, when you d/l the patch, just double click on it, and enter the path (i.e. C:\Program Files\OOTP5), and click next, and it will unzip.
Now, it's very possible you need a file-extracting/unzipping program such as WinZip, which can be found here:
http://download.com.com/3000-2250-10161502.html
It's free to try -- not sure of the details, but $29 to buy. Hope this helps. If you have any other questions whatsoever, feel free to ask.