assuming you've not run before, or haven't run in along time. If you're worried about gait or flat footedness, then get some proper advice, personally, I've never felt the need, but I know I'm lucky in that I'm a "pull on trainers go run" sort of runner, and not every-ones like that.
Once you're sorted for foot wear; actual running? Find a flattish (maybe a small hill) course of about 5km long, and run it, slowly, and if you need to stop and walk then do so, but aim to run it all. Do this 2-3 times a week, for about 4-6 weeks, you'll be screamingly bored by the end of the 6 weeks, but what you're trying to achieve here is getting your body used to running. Don't time yourself, in fact don't even wear a watch, now is not the time to be setting PB's you've your whole running career ahead of you to do that. Just get used to running.
Once your comfy running the route, then you've a couple of choices, aim for a speed increase or a bit of distance, or preferably go for a mix of both, again start increasing it slowly, and steadily.
If you get an injury, anywhere on yourself. STOP RUNNING, and walk home, ice any inflammation, and rest for a couple of days before trying to run again. If you're still in pain, leave it a bit longer, still in pain after that? go see a doctor.
I wouldn't go off road straight away, you need to develop a bit of strength and flexibility first, but running through a dappled forest with the birds singing, and peace and quiet all around, is one of the greatest joys of running IMO.
HTH
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