1. Download the most modern non-beta version from here. (select the version of your systems OS type like 32bit or 64bit)
2. Install using default options.
As default 7-Zip installs itself to with “explorer extensions” that allow you to right click on items on the desktop or in windows explorer to compress files. Z-Zip has its own file format 7z which is more efficient at compressing files than the standard zip extension, but this will mean the person you are sending the file to will also have to use 7zip. Using the zip format will enable people using other programs to de-compress the file.
1. Right click on the files or folder you wish to compress and encrypt.
2. First change the archive format to Zip, then change the encryption method to the robust AES-256, thirdly enter your password. Then click OK. The rest of the options can be left as default.
Simply right-click on the file, select extract then enter the password when requested.
Please your password a mixture of numbers and letters rather than simply a single English word. One way to protect from this would be to use a random generated password or use asymmetric encryption.