Deciding how much to run each week means you first need to consider a number of factors. The first, overarching factor to consider is your overall running goal (or goals). What are you trying to do or accomplish through running? Are your goals directed more toward staying shape, losing weight, toning muscle, or just reaping the mental and physiological health benefits of running? Or are you focused on actually improving your running form, running pace, race times, or have a particular race goal in mind? After asking yourself these questions, next consider your personal running and injury or health history. Have you ever ran in the past, and if so, what kind of running? (I.e. were you running longer distances, shorter sprint distances, running within a team sport, or just an active child or young adult who liked to get outside and play?) Do you have any sustained injuries that might flare up, such as a "bad" knee or hip?
Once you have determined what your goals are, and what past injuries or past running history you have to work against or build upon, then you can really start to think about how much running is best for you. At the beginning, you will likely find that running longer distances consecutive days in a row just does not cut it for you. And you definitely should not push yourself too much at first. Running too far and too much when you are still a "newbie" is pretty much the fast lane to getting injured. Similarly, you do not want to try and run too fast when you first start out either, or else face burn out in the middle of your out-and-back loop, leaving you exhausted but still having to huff it back home.
My suggestion would be to start with a goal of three times a week, choosing to run on non-consecutive days so that you can give your body a break and the chance to properly recover. Start out with a goal of running just one mile without stopping (if you have to stop and walk during your first week, it's okay! But don't give up until you have ran a whole mile without stopping). From there, increase your mileage by half a mile every week. This will help you build a solid running foundation while keeping you strong and injury free. Soon, you'll be ready for a 5k, 10k, or even half marathon race distance!