I don't mean to sound rude but what you're asking leads me to believe that you haven't really done any research into this. Walking a certain EXACT amount of steps won't help with realistically anything, other than ...well counting your steps. If your goal is to lose weight, the NUMBER ONE thing you need to focus on is your diet. Given that your diet is proper, you will lose weight regardless of what activity you're doing. I can link you to a bunch of articles about this, but I think you should research some of this on your own. Nonetheless, I'll give you some tips on how to achieve what you want.
First of all, forget about this correlation business. Weight loss, nutrition, etc are NOT linear processes, and vary on the individual greatly.
My best advice if you want to lose weight, would be to follow an established diet like a low-carb high fat (since you're only walking, you don't really need carbs for any intense exercise, other than fibre of course). A good baseline, would be to take your bodyweight in lbs and multiple this by 14. That's more or less the amount of calories you need to maintain the weight you're at right now. So depending on over how long you want to lose this weight, for example, if you want to lose about 0.5 lbs a week, subtract 500-600 calories from this number and achieve to consume that amount every single day. So if you weigh 165lbs, then you would need approximately 1700-1800 calories a day to lose half a lbs each week (note again this will not exactly be linear).
Of these calories, since you'll want to maintain muscle, make sure you get at least a gram of protein per lbs of bodyweight, i.e 165g since more muscle equates to higher metabolic rate. Around 20-30% of your calories should come from fat, and the rest from low glycemic carbohydrates, focusing on fibre.