Develop Google Chrome Extension Type & Translate Instantly

I want to develop a simple google chrome extension which will translate immediately after typing. I will type in English and will translate to Chinese FEATURES - I will be able to add websites where this extension will work only. - As soon as I type something on that website such as in Searchbar, Comment bar and it will translate it to Chinese. As a example I will visit [login to view URL] and as soon as I type "Baby Toy" in the search bar then it will translate & change it to "婴儿玩具". It should be simple and easy small task.