That is tru, they don't provide 8051-based schematic, but what they do, they show you the way you can control houshold devices. Somehow you will need to connact a switch to 8051 and another 8051 pin will have to activate a relay (solod stste relay, or similar) to turn a light ON or OFF.
On the other habd, 8051 in its standard configuration has only limited number of pins, so you may cosider port(s) expansion to increase the number of I/Os ..
Count how many devices would you like to control, and which way would you like to connect switches/relays and we can come up with a digram of 8051-conroller for your installation..
Regards,
IanP