Hi Farhana,
There are a few mistakes and things you can do to improve these sentences, but they all make sense, so great job! I will add a few corrections to help a little :) Although there may be better words or phrases to use, I will do so using your own words as I think that will help more.
1) Was that how your parents taught you to behave with teachers? ( one of my friends behaved badly, so I asked this question)
As a general phrase we tend to say 'Did your parents teach you to behave this/that way?'. It isn't necessary to put 'teachers' in this case because the context is probably already clear. You would only really use it if you were o ask them this question after some time since the event happened.
2) When we will come out this generalized, confined thinking of calling a bearded guy with a cap on his head as Rajakar?
This is good but to be more natural (using your words) I would say:
When will we stop this generalised, confined way of thinking that a bearded guy who wears a cap on his head is a Rajakar?
3) When the new and upcoming generations will read these distorted history, they will surely fall for this propaganda that a bearded guy with a cap on his head is Rajakar.
To make this more natural (using your words) I would say:
When future generations read this distorted history, they will surely fall for the propaganda that a bearded guy with a cap on his head is a Rajakar.
Hope this helps :)