Most folk can't just go out and "run". It takes practise, and everyone is/ was at where you are now. There is excellent advice on this thread already, so I will try not to repeat it (but probably will!)
Do you run on your own? If so, try and get some one who can go out with you, it will help... it will motivate you too. Go at the slowest pace of the two of you.
Couch25k.... definitely. This will give you little goals to achieve each week. By the end of the programme, you will also be able to see how far you have come. Keep a record of what you have done each session, so you can look back and measure your success.
Balanced diet... yes... and use this in conjunction with the running. The latter does not mean you can eat what you want! Get the weight off in a sensible manner. Running + sensible diet will work!
Dont be worried about taking walking breaks, its all part and parcel of you learning to run. Once you get a lttle fitter, bit less weight, you will find that you can natually run for a longer period.
Above all, enjoy what you are doing. You have made the decision to run, and lose weight, just do it!, and glow in your successes!