Install and launch VirtualDJ on your computer. When the application opens you will be presented with the main screen. Practically all the functions you will need when DJing are on this home screen, which prevents having to switch between multiple views in a live situation. The virtual "Decks" are visible at the top of the screen, with the mixing controls in the space between them. The lower half of the screen displays the audio library, where tracks can be selected and dragged up to either of the decks to be played.
Access your music collection using the browser window in the lower half of the screen. The smaller portion on the left-hand side of the screen includes a folder tree. Within the folder tree, the uppermost section "Volumes" shows all the physical drives connected to the computer. From here it is possible to drill down through the folder tree to any location on any drive. Music folders can be bookmarked as "Virtual Folders" for ease of access in future.
Select a track from the music library and drag it onto "Deck A." You will likely notice a second or two or processing before the file plays. This is because the first time VirtualDJ plays back an audio file, it scans and analyzes the contents in an attempt to detect the beats per minute (BPM) and genre, which it later uses to organize music in the library, grouping similar tracks together to aid the creation of sets and playlists.
Use the individual "Play" and "Pause" controls on each deck to control playback. The cross-fader in between the two decks is used to fade between the two decks. If you have a multi-output soundcard, a headphone signal can be routed to the secondary output, allowing you to pre-listen to tracks before moving the fader over. An essential function for DJs, it allows them to ensure the two tracks are synchronized before fading up the second song.