How to treat congestion by draing & cough from my throat every day?

Find the cause. While there are several medications that may help improve symptoms of nasal congestion, post nasal drip and cough, the best approach would be to identify why the symptoms are occurring. Possibilities include allergies, chronic sinus inflammation or infection, and even stomach acid reflux. Especially since the drainage is "every day", see a specialist ENT or allergist who can find cause.