The best place to let dough rise is a very warm place. On a warm day, your counter will probably do just fine. But if your kitchen is cold, your oven is actually a great place.
Preheat oven to 200 degrees for 1-2 minutes to get it nice and toasty, then turn it off. Place the dough in a greased bowl and cover with plastic wrap, then put it inside the oven and let rise until doubled (about 45-60 minutes).