can you tell me the ethics when we are travelling in flights?  

Before take off the pilot and the airhostesses will demonstrate and explain do and donts while travelling. It is simple and easy to follow. Bon voyage..

Hi srija ,
I have travelled a number of times in flights all over the world. As samsun said the airhostess will tell you dos and don't during travel. Happy Bon Voyage

When you go on your first flight then air hostess will provide a full demonstration ... about your question... and give some ideas to spend great time in flight... you should go to any tour on flight... it will be a good experience.

Hi, I could say Flight is another carriage just like train or bus :) its not a big deal as such. Before takeoff the airhostess will demonstrate how to put on the seat belts and use the emergency door etc.
And when its domestic short distance flights they might serve some bewerages/snacks (at times its free at times to be paid for). If its international flights you need to infrom the airhostess as to what kind of food you need, Veg, Non Veg, Only Chicken, Asian meal or so. Be careful when you say Non Veg - Right from Chicken to Pork everything would be served as non veg unless you specify what you need out of the options they have. In international flights there would be a monitor normally for watching some movies. During takeoff and landing for the first timers there would be a kind of fear just like one might have in the roller coaster. But its just for few seconds or harldy few minutes.