Click here to download Python 3.
Run the installation file
After you finish with the installation, go to the control panel
Go to system, then 'Advanced settings'
Click on 'Environment Variables'
Under 'System variables' click the variable called 'Path' then the 'Edit...' button.
Without deleting any other text, add C:\Python36; (include the semi-colon) to the beginning of the 'Variable value' and click OK.
Click OK on the 'Environment Variables' window
Open a new command prompt window type python, you will have python running in the command prompt