Yes, you can grow a full tree from just a pit. The techniques has already been covered and growing the tree just takes a warm climate which, in my Southern California experience, means no chance of freezing. I acquired a 5 foot tall tree from my neighbor and after planting it in my yard watched it go to 30 feet tall in about two years. Got the first 10 avocados after three years from germination and before moving and having to leave the tree behind, was getting a hundred or more avocados that rivaled any in the stores.
When starting the seedling, just need to be sure it has not gone into the refrigerator. My experience is that the pit won't sprout if it has been chilled.
You have to live in parts of California, Peru, Mexico, Florida, or a similar climate, for the avocado tree to survive outdoors. If so, I highly recommend it, along with a lime tree and a lemon tree. =)