Generally you want to just start slowly increasing your weekly mileage. In the beginning you’ll be less concerned with completing the miles from an endurance standpoint and more worried about getting your body used to the impact of consistent and extended running in order to avoid injury.

My personal recommendation to start off is to incorporate a single long run of 8-10 miles once per week into your training on the run before your rest day. After a couple of weeks you can reassess how you feel and start to increase your overall weekly mileage on your normal workouts during the week. Just listen to your body and don’t push it too hard because stress injuries will keep you off your feet for a very long time!