New Twitter API requires authentication, you need to go to dev twitter and to create tokens. See documentation
You need to use a library. I use this one
EDIT: You need to create an application on dev twitter (it’s just a basic information, fulfill the form) and then you’ll get access to your tokens. The library will manage connection to the API if you have those tokens.
I wrote a lot of articles about that but it’s in French so I doubt you will read them and I’m not here to advertize. Probably a better idea to read articles from this website