I highly recommend first downloading and reading the smaller Revolution - U User's manual. Many of the Titan connections are the same as the Revolution's connections. I find, for someone new to QSI, it a little less complicated. The knowledge base can then be built upon with the added information from the other manuals.
Also, Nick mentioned the blue wire. Technically, the unregulated blue wire (most people call it +12 Volts) is whatever track voltage minus the voltage drop of a full wave bridge rectifier (1.4 Volts). Our club has it's track voltage set at 12 Volts so the actual voltage on the unregulated blue wire is 12 - 1.4 = 10.6 Volts. Since it's unregulated, if the track voltage wavers the blue wire voltage wavers as well.
The red with white striped wire is a regulated (steady) + 5 Volts.