Download the packages from Microsoft
Packages with PowerShell is available on the project page on GitHub. Download appropriate for your operating system. Examples:
For Linux Mint 18: Download a package with a name ending in "16.04.1_amd64.deb".
For Linux Mint 17.3: Download a package with a name ending in "14.04.1_amd64.deb".
To install, double click on the downloaded package.
How to run PowerShell in Linux Mint
Open a terminal, type "powershell" at the command prompt and press Enter.
To exit, use the "exit" command.