Descend into symbols that are attached to schematics by mouse box highlighting of the component symbol and pressing the keyboard "d" button or ctrl double clicking on the symbol. The "d" is probably better since if the component is inadvertently moved it may destroy its wire names. Alternatively, mouse over the component, and right click. and select the "Descend into schematic" menu item from the pop up menu.
There is more than one way of setting up a schematic hierarchy. The schematic can be first drawn from scratch, or symbols can initiate a new schematic with schematic subcircuit pins automatically placed on the schematic. If a symbol has been set to be attached to a schematic, an attempt to descend into a nonexistent schematic, will automatically initiate the creation of a blank schematic with subckt pin connectors already placed.
See Create Symbol for more information on connecting existing/newly created schematics to symbols. This is an easy way to create a symbol and make sure the symbol matches up with its pins. After the block symbol is created, it may be edited, e.g. add angled wires etc.
See model and symbol attachment for more information on connecting symbols to schematics.