Another newbie

Hello, another my fitness pal newbie here. I just started on monday. I have about 36kg (80lbs?) to lose and a hell of a lot to gain.
I am a mum of 3 beautiful kids and 1 Angel baby and I never lost the weight I put on during pregnancy with the last 3.
I also have quite a major back problem, the neuro wants to operate but agrees that a weight loss could pospone surgery and help with pain managment.

I have tried before but the motivation was never there to keep going, the last time I lost over 20lbs but have let it creep back on.
THIS time is different......