Stay at home moms

Hello i am a stay at home mom ages 8, 5, and 3. my oldest is a special need child. Since having my last child i never lost the weight, I weigh 179 at 5ft 2 inches, this is the same weight i was at the time of my 3 child birth. I never dieted before so im looking for support, It's going to be very hard but im doing this so i can be more activite with my kids.