The following screenshot gives a basic overview on the different components of DynamDJ. You can click on one of them for more information.
The part above the fader are the 4 players. Per player, one audio file can be opened and played, and effects such as an equalizer or a pitch shifter can be applied using the controls inside its colored area. The fader can be used to define which players can be heard, you can do this by moving its knob under one player or between two.
The four components below the fader are not directly connected to the four players, and can be shown or hidden by clicking the window's zoom button, which is the third button in the title bar. The room placement component is useful if your audio configuration consists of more than two speakers that are placed in different parts of the room: you can move players around in a visual representation of it, and their volume on each speaker will be set in a way that the sound will seem to issue from this physical location. The audio input player allows you to use live input from a microphone (for example), the Speech player gives you access to the Speech Synthesizer of Mac OS X. The rightmost component shown in the window is the master player. You can set global sound volume and balance with it, and record the audio produced with DynamDJ to a file.