There are different types of broadcasting, but most commonly broadcasting is attached to empathy and telepathy. If one thinks of an individual as a radio antenna that both sends out signals and receives signals then the concept of broadcasting is much easier to grasp. Everyone is able to receive general broadcast thoughts such as another individual's mood. This is how humans can quickly judge situations and react appropriately to them. In this manner everyone has the raw ability known as Broadcast Empathy. Through practice, or through familiarity with another individual, one may extend their broadcast empathy ability from moods and emotions to the surface thoughts of another individual. Though broadcast empathy allows for the reception of surface thoughts it does not allow for deeper inspection of thoughts. Anything other than surface thought reception requires a connection.
Broadcast Telepathy generally occurs all the time; however it ca be controlled with practice. Any thought that comes to the surface of a person's brain is broadcast out for anyone to receive. If a specific thing is to be broadcast it must be brought to the surface of the brain and held there for a while in order for its broadcast to be strong. A person may keep their broadcasts in check through the use of shields, filters, or masks, but an individual may simply choose to hold a single thought on the surface instead (to continually broadcast only one thing). Telepathic broadcasts are not private, so any private telepathic conversations need to be done with a connection.
Remember that neither empathic, nor telepathic broadcasting violate any rules, but it is common courtesy to keep telepathic broadcasting to a minimum so as not to overwhelm other individuals. Broadcasting requires no visualization, just thoughts, and it is a natural ability, like breathing. With practice just as a person can control their breathing they may better control their broadcasting abilities.