I am not a trainer so hopefully more of an expert will respond soon. However, IMO I would start in a very small area with a little lead to teach her the command. You will have to SLOWLY make the area bigger and bigger and move from having no distractions around to slowly introducing her to the command with "controlled" distractions that you plan ahead of time (ie., loud noise, someone walking by, etc.) and just praise praise priase praise her. Until she gets it, I would never let her off lead outside; EVER! When training Monkey, I also tethered him to me and he just followed around anywhere I go. Whether inside or out.
Good luck!
Peggy, Monkey & Maddie
