if you know that 7* 8=56 , how can you use the commutative (Order) Property of Multiplication to find the product of 8*7 ?

Answer 1

you just did. The property means that
8 * 7
is exactly the same as
7 * 8

In other words the two factors commute, you can change their order without changing their product. This will be true until you get to multiplying matrices.

Answer 2

http://coolmath.com/prealgebra/06-properties/02-properties-commutative-multiplication-02.htm

Answer 3

Remember back when when you were learning addition you had the commutative property of addition which means
2 + 3
is the same as
3 + 2

Now you are getting the same property for multiplication :)