Well first I'd say that you've taken a good step in deciding to get fit. YAY you
Next don't put yourself under pressure if it's some time since you've run, or you haven't before. There's no need to even run at first, build it up, maybe do some fartlekking (sounds rude...isn't) on there....which can be walking then running then walking and so on.
You're really just looking to build your stamina up and get those muscles used to you moving in that way again at first.
So maybe do five minutes walking as part of your stretching and then a five minute light run and then walk again to start with. Frankly anything is better than what you've been doing if that's nothing!!
Don't worry, at this stage, about putting an incline on it or on your speed, just concentrate on building up your distance and time gradually.
Oh and don't be shocked if you step off the treadmill and go road running if your muscles hurt like a mother after! A treadmill tends to work different muscles to road running, which was a nasty shock to me and my achilles one year!!
And good luck