Just an aside, gym bros are one of the most friendly, educating bunch when it comes to new comers. Everyone starts somewhere (even the gym bros) and if you are willing to go and ask, they are likely willing to help you get started.

Start on the treadmill walking, lift the easy to learn machines, and stick to a routine. Diet is a great first start. Follow up with exercise. It'll help you keep the weight off and extend your life.

Keep at it.