How to Unzip a 7Z File
A 7Z file is a type of archive, which means it's a file that holds other files inside of it in order to compress them and make them easier to transport. 7Z files are different than files commonly opened by programs such as WinRar that deal with the ZIP or RAR format, because 7Z files are more tightly compressed. This means that in order to open a 7Z file, you'll need to get a program that focuses especially on that file format.
Go to a site that has a program that can open 7Z. An example is 7Zip (see Resources).
Click on the "Download" link and then click "Save File" when the download screen comes up.
Find the installation file after it finishes downloading. It should be in your desktop or "My Downloads" folder. Double-click on the file to begin installation, which will include choosing a directory for your program.
Find your 7Z file and right-click on it after installation is finished.
Select "Open With" and find your archive-opening program, and click on that. The program should now begin to open your 7Z archive.