New to site. Need support and tips to lose 70+lbs

Im Kayla. 20 years old. I have a 20 month old baby girl and from my pregnacy i gained this mass amount of weight that will not go away. I am new to the sire and could use all the help I can get. I have always been over weight but this is my bottom. I am 5'1 and am at (220). I should be around 130 for my height and age says doctors. So I need to lose over 70lbs to be at a normal health weight. I have never dieted before so Im up for any suggestions that are a safe and healthy way. Feel free to add me if you feel we could support eachother because having support is one of the main keys to losing weight and keeping it off.

-Thanks

Kayla