Thanks for writing your query.
Your teeth discolouration is due to heavy smoking
and lots of tea and coffee intake,these stains will not go after simple brushing.
So i would suggest you visit a dentist
in your area at the earliest and get the scaling and polishing done,if stains will be there even after scaling and polishing you need to go for bleaching.
Maintain good oral hygiene
,brush twice daily,and follow biannual dental check up.
And leave smoking at the earliest otherwise it may lead to serious oral health problems along with staining.
Hope this will be helpful.