There are several ways in which you can get material for radio news bulletins.
The first way in which you can get material for radio news bulletins would be by employing reporters to report events as they happen.
The second way in which you can get material for radio news bulletins would be by signing up with news agencies, from which you can buy news reports to air on your station. There are agencies whose business is that of collecting information, and selling the reports to broadcasters and print media operators.
The third way in which you can get material for radio news bulletins would be by getting the listeners to report events as they observe them. To this end, you may even sign up for a Ymail account at mail.yahoo.com, and then give this address to the listeners, for them to be reporting things through it. This approach does, however, require some verification, because some mischievous people may decide to use this system to report things that are not factual. Still, this user-generated model can work wonders, especially if it is backed up by professional reporting. That would be an arrangement where you get reports from the listeners on where things are happening, and then use such information to know where to send reporters.