How to connect stackstorm with web app (third party) using http request

hi all,
i want to connect my web app with stackstorm using http request . what is the procedure for it …i can access my web app using core.http action from CLI …but now i want to create Rule for it …i have read all doc of stackstorm and i got some idea about that …but i don’t know from where i have to start …i have created one rule also for it but i don’t know how to trigger it …i don’t know how to create sensor in python. and what the code is required in sensor… don’t know about trigger…waiting for help