Subcircuits offer a reusable and tidy way of using a circuit, when you're only interested in interacting with external connections to the circuit. The subcircuit is creating as an IC, with the pins acting as the interaction with the internal circuit.

First, the circuit to be used in as a template for creating a subcircuit from must be constructed. The points of interaction are defined via External Connection components. These must be connected up, and positioned where you want the pin to be positioned on the subcircuit IC.

Next, select the group of components and external connections to be turned into a subcircuit, and select Create Subcircuit from the right-click menu. You'll be offered to enter a name for the subcircuit. Once created, the name will popup in the Components selector under the Subcircuits selection. This can be treated as any normal component - with the additional option of removing it by right-clicking on the item and selecting Remove.