You may have very good reasons for not wanting to allow friends to create and share posts on your FB page. But if you want to change the settings and allow this, here is how. Note that these screenshots were taken on a laptop, not a cell phone. If you do this on a cell phone, the display might be different.
Click on the downward arrow at the top right of your FB blue ribbon. A drop down menu should appear.
On the next screen, General Account Settings, find and click on “Timeline and Tagging” in the left menu bar.
Review the Timeline settings. It should say either “Friends” or “Only Me.”
If you need to change that, click on the “Edit” link, next to the pencil icon. A drop down menu should appear for you to select the setting you want. At this time the two choices are “Friends” or “Only Me.”
Once the settings are changed, click on “Close” link and you are done!
You can continue using Facebook and the settings should stay like this until you deliberately repeat the process to change them.