I like working with local businesses when it comes to home improvements. Just Carpets on US Hwy 9 Howell has a large selection, competitive prices and are in business for years. They also have a good website showing all of the products they carry..
Even though you've already bought the carpet, you can still call technicians who sell carpet as well. Most technicians will work with the carpet whether they sold it or not. I would suggest talking to anybody you know who has had carpet work done recently. Get as many recommendations as you can so that you can talk to a lot of companies while deciding who to hire. http://www.hardwoodfloorsandmoreinc.com/Products/Carpet/
I would ask about in your area so you can find a local installer. I think that getting new carpet is a great way to improve and change up your home! I would like to get some new carpet for my living room. There are so many different colors and styles so it will be fun to pick some new carpet! http://www.mobilecarpetone.com/
Not exactly sure the area you need the installer for? Although I usually like to support local installers..some clients of mine have had good luck with Home Depot..not sure if you need to purchase carpet through them or not though. Good Luck!