In order to install elements from the PowerShell Gallery, you will next last version of the PowerShellGet Module as indicated in the PowerShell Gallery website:
https://www.powershellgallery.com/
If you don’t have last PowerShellGet Module version, you can download and install it from the following Url: https://www.microsoft.com/en-us/download/details.aspx?id=51451 (PackageManagement PowerShell Modules Preview – March 2016). Once you have installed it, you will be able to save and install any PowerShell module coming from the PowerShell Gallery.