1. python and pip
2. Flask
3. PyMongo

After installing python from offical site you will get pip and using it you need to install last two packages

pip install Flask
pip install Flask-pymongo

there are two types of enviorment in Flask Production and Development so you need to choose one of them according to your requirement

using following command you can set your enviorment

for windows
set FLASK_ENV = Development or production

for linux
export FLASK_ENV = Development or production

After that you can run Flask web app using 2 ways

flask run

following line is last line of your app.py file
app.run(port="your number",Debug="true or false",host="ip")
python app.py