When we say that all media messages are constructed, we mean that all media messages have been assembled by someone. That “someone” could be a single person, or it could be a large organization. The messages and values embedded in this particular piece of media are those of the people who created it.
In photographs, the photographer's own vision of what she wants to show within the frame demonstrates her own values and beliefs. A newspaper writer’s articles may be based on his own beliefs, or based on the beliefs and ideologies of his publishers, or perhaps even the beliefs of the companies who advertise in that particular newspaper.
Since all media messages are constructed using the creator’s own ideologies and values, media messages from different creators will have different ideas imbedded in them. The ideas embedded in each piece of media come from the creators’ own experiences, and since everyone’s experiences are different, we can expect that each media message should be different as well.
The reason this is important is because not all media messages will have messages you agree with, since your experiences and ideologies will be different from those of the message’s creators. While you may experience a certain media message in one way, there are others who will most certainly experience it in a completely different way. For example, while you may find a particular media message amusing, there may be others who find it offensive.
The media message's construction isn't only based on the creator’s own ideas and ideologies, but also on a pre-defined set of rules for that particular type of media. A photographer uses camera angles, lighting, and lens length to get her ideas across, while radio producers use voices, sound effects, and music to get their ideas across. Each type of media must adhere to its own set of rules in order to construct the intended message.