How Can I connect a generator into my house electrical supply?

To properly connect a generator into the house wiring, to operate the homes electric system, they sell a special box, this box will disconnect the main feed line while the generator is in use. This prevents a feed bask on they system.

For selective circuits, consider a product such as this:

Reliance Manual Electric Transfer Switches for Portable Generators (http://www.mastersalesonline.com/protran/index.html)