I installed Python and I am using it in VS Code, but, when I install libraries in Terminal via `pip3`, I get an error telling me that `pip3` is not a command.

I also checked for my version of Python and I get this other error:

![The Error of CMD that show command not found](https://i.stack.imgur.com/PRO6Q.jpg)

What should I do to fix this?  

My python is `3.8.3` for `Amd64` and it is installed in under `D:\Python\Python38\python.exe`.