How many calories do you burn?

okay i walked 3 miles today because i want to lose weight. i want to know how many calroies would i burn by walkin that many everyday and then moving up to more and more miles. i want to lose 10 pounds but i want to do it the right way so it stays off. i have been eating fruits and veggies well juiced anyway im not sure what else to do to acheive my goal. maybe you guys can give some pointers as well.