There is (nearly) unlimited help for any given math topic available online. Google is a great place to start if your child is having difficulty and you don't feel comfortable helping them. YouTube has thousands of videos over math topics as well.
A few helpful websites are:Khan Academy has great video tutorials for math topics from elementary to college level. They also have many other subjects as well.Purplemath links resources for help in mathIXL Math (free trial, but will require payment after the trial period)There are plenty more out there! Look around!