Go to profile menu, click on Edit Profile, on left hand side click on API and create a new key, because you didnt mention any programing languge i will go with CURL

curl -X GET "https://api.themoviedb.org/3/discover/movie?api_key=YOUR_API_KEY&with_genres=28&sort_by=release_date.desc&language=en-US&page=1&include_adult=false&include_video=false" -H "accept: application/json"

Thank you. I will be using Java for the development. Would you be able to help.