Generally speaking, all the Members who wish to be notified of the activities occurring in the Places they are a part of will see the message(s) and comment(s) you post on those Places. Likewise, if any new members are added to a Place, or a sub-Place is created under a specific Place, other Place members will be informed.
Your messages and files on your personal Place will not be available to anyone but yourself. Similarly, any Place which has restricted access levels fixed from its Place settings will be only accessible to those Members that the Manager(s) has set to have access for. To read more, see our section that has specified user access levels.