7-Zip is indeed a good product but such file compression software is largely unnecessary these days, because Windows has the facility built into it.
To unzip a compressed file in Windows, simply double-click on it.
To create a 'zipped' file in Windows, first highlight all of the relevant files, using the standard Windows techniques. (i.e. to select all of the files in a folder press Ctrl A. To select a block of files, click on the first one and then hold Shift down when clicking on the last one. To select lots of individual files, hold Ctrl down while clicking on each one in turn).
Then right-click on any of the highlighted files and select Send To > Compressed (Zipped) Folder.
Easy peasy!