how to use pip install conda environment

Open Anaconda Navigator
Select Environments in the left hand pane below home
Just to the right of where you selected and below the "search environments" bar, you should see base(root). Click on it
A triangle pointing right should appear, click on it an select "open terminal"
Use the regular pip install command here. There is no need to point to an environment/ path(shrink_venv): pip install Pillow

Requirement already satisfied (use --upgrade to upgrade): Pillow in /Library/Python/2.7/site-packagesconda create -n shrink_venv