you haven't specified any details - just a (wide) topic as already stated it can be very very simple project to a very complex project .
by which means you need to control the devices , direct , rf , ir , lan , internet ..? are you planning to use a microcontroller or using descrete ics ?
You have to sit down and dissect your project into some blocks.
you may wonder why the people give such responses . a search for 'help' or 'urgent' in this forum will give you the details.