Not every liquid-cooled system has a fan, but most use one to help the radiator dispel heat faster. Similarly, not every system has a separate reservoir. Those that don't generally have a fill/bleed line for adding coolant and removing extra air from the system. Usually, the fill/bleed line leads to a filling port at the top of the computer's case.
In a liquid-cooled PC, the tubing presents a special challenge. It has to be flexible enough to connect components that may be at odd angles to one another. But it can't be prone to kinking - a kinked hose can severely restrict the flow of fluid through the system.
In a simple system, a tube connects the pump to the inlet of a water block. Separate tubes run from the water block's outlet to the radiator and the radiator to the reservoir, which often sits in one of the computer's CD-ROM bays. The final tube connects the reservoir back to the pump. For systems with multiple water blocks, tubes connect one block's outlet to the next block's inlet, connecting the blocks in series like a daisy chain.