Catnip?

I have 5 cats! I was at a pet store and I bought a little container of live Catnip. How do I grow this stuff for my cats?? I planted it in a large pot to get it going.. Please give me some tips in growing a larger patch of this in my yard for my cats? Does it spread? Do I need to dig up a section of the lawn or is it more dominant that Kentucky Bluegrass? Sun or shade? Water? I am in Colorado, we have cold winters. Please give me some tips, I would like to make a little place for my cats in the yard. Thank You!!! :)