Desperate for something attractive to use as ground cover, I've purchased 100 hybrid lily bulbs and now I need to get them in the ground. How closely can I (should I) space them to get maximum coverage in the shortest period of time?

I'm a total garden novice who purchased a home two years ago with a small lawn that has 20 flower beds! I have one bed that is 20 by 40 feet (sun varies, but all parts get a minimum of 4 hours) and another in the shape of a grand piano that is 40 feet deep (full sun from 8 am to 4 pm). And that's only 2 of the 20!

So, your help would be greatly appreciated -- how closely together should I space the bulbs. AND, as long as I'm soliciting advice, how deep should I plant them? The bulbs arrived last night and I can see that they are starting to sprout--they all seem to have an inch or so growth (which will at least make it easy to tell up from down!).

Thanks for any help you can offer!