Hi, Barb! First of all, six weeks is so very young -- most Shelties aren't separated from their mothers until 8 weeks at the earliest -- my breeder keeps her pups for nine weeks. Right now, you have an immature baby who really isn't ready to potty train for another three weeks. But take heart -- there's hope.
I would agree that puppy pads would be a good idea for three-four weeks, both in her crate and in a convenient spot in the house. You and your floors deserve that much! But after that time, stop using them. (By the way, I hope you have a crate in your bedroom for night. Puppies bond to you by breathing in your scent all night. Yes, she may whimper to go out at 2 am, but she'll be able to sleep through by 9-10 weeks or so. My Layla came to me at 8.5 weeks, and she slept from 9 pm to about 5:30 am.)
You probably do this already, but take your baby out every 2 hours. Take her on her leash to the same spot every time. As she romps, you stay in the same spot. Repeat, "Hurry up, Hurry up" in a calm, gentle tone. The idea is to condition her to associate those words with piddling. You can use "Go potty" or anything else, but be sure you always use the same words. Don't issue it as a command, but in a pleasant voice. Try not to get frustrated with her. If nothing happens after 15 minutes, bring her back in. For a few weeks, there will probably be accidents. Remember, she's really not ready to potty train yet; you're just starting to build the right habits.
And when she does go outside, make sure you praise her in a big way!
I strongly recommend the book The Art of Raising a Puppy" by the Monks of New Skete. You can get it on Amazon for as little as $3.00. It's the best guide I know. We've raised three according to the Monks, and people are always remarking on what calm, gentle "perfect" Shelties they are.
http://www.amazon.com/gp/offer-list...r_olp_1?ie=UTF8&s=books&qid=1210266824&sr=8-1
Best wishes on your little darling!