open windows powershell with (run as administrator) paste below command in it:
Set-ExecutionPolicy Bypass -Scope Process -Force; [System.Net.ServicePointManager]::SecurityProtocol = [System.Net.ServicePointManager]::SecurityProtocol -bor 3072; iex ((New-Object System.Net.WebClient).DownloadString('https://community.chocolatey.org/install.ps1'))
You have successfully installed chocolatey in your system you can use chocolatey from anywhere in your system. Now close the powershell