I just received a query from someone with a new Fan Page on Facebook. She was frustrated because she could not Share posts that were made to it by other people.
A quick investigation, which is play for me, came up with the answers.
First, to manage you page select your Page Identity from the Dropdown menu by clicking on the arrow in the upper right. Then choose the Settings you wish, including the one to allow posts to your page.
Now go back to your Page. Any posts made by others will be appear in the column on the left. Click on the arrow to open up a list of the posts with the option to Like, Comment or Share.