how do I unzip it?
You may already have a program for unzipping zip files on your system.
Right click on the zip file and choose an option that says something like: "Extract files..." or "Extract here"
If that doesn't work download a program like winrar ( do a search on google ).
There are many such extraction programs one can download for free.
I use a version of winrar that I have had for many years. I don't know what the best program is these days.