Hi Bibi, welcome to TAI. Please introduce yourself in the Introductions thread and feel free to tell some thing about you.
You have not mentioned the model of screen you are trying to fit in your Teana. However, it is very much possible to replace the factory fitted screen with a high definition display screen. Please try a Google search for 'GPS Unit Installation Guide For Nissan Teana' which will give you some good links on this. Also take at most care that the display screen is of the correct size and can work seamlessly with the Nissan main module assembly. This needs some expert knowledge hence I will suggest you to check with Nissan authorized showroom as well. There are lot of DYI experts in TAI. Let's hear from them too.