From the project directory, do:
cd backendmkdir venv to create a directory for you virtual environmentpython3 -m venv venv to create the virtual environment in backend/venvsource venv/bin/activate to activate the virtual environmentpython3 -m pip install --upgrade pip to update pippip3 install -r requirements.txt to install python dependenciesexport FLASK_ENV=development to configure flask to use development mode with hot reloadingpython3 app.py to start the serverpip freeze > requirements.txt