Which light is better for corn snakes?

I've heard to use a red heat light for corn snakes, but I went to my pet store and the only red lights they had, said to use only at night. They had blue day light heat bulbs would those work? what's the difference? Can I use a night light for the day? Also (this doesn't have to do with lights) when using aspen bedding, should i also use terrarium liners? or is the bedding fine by its self?