I need a detail list of the steps to install otree studio on Windows 10.
What must be installed first?  Powershell?  Python?

I've installed Python, and installed powershell.
Next step is to enter the command: pip3 install -U otree 
in powershell. 
When I do this, it says that pip3 is not the name of a cmdlet, function, program etc.
What am I missing?

Hi awallen, just use pip instead. pip3 is typically used for Mac OS. 

I would suggest you to create a local virtual env to better use otree command. Take a look at this tutorial: https://python.land/virtual-environments/virtualenv