Image Sharer allows you to post to FB to both your feed or to the Facebook Page's that you manage.
If you click "Not Now" during your Facebook setup to Pages and wish to add it later, you will have to remove Sumo App from your Facebook apps and re-add it.
Log into Facebook and go here:
If you do not see Sumo click on "Show All"
Find Sumo and remove it by hovering over it and click in the X.
Now go back to Image Sharer and reconnect to FB, this time say Okay :)