Option 1: How to Post on Facebook Page via Web
1. Using any browser, Login on your Facebook Account
> Click Home
> Click on your Facebook Page Shortcut
2. Click Create Post
3. Type Something/Content to Share
> You may also include Link URL on your Post
> Your Post, by default is Public
> Finally, click the Post button
Option 2: How to Post on Facebook Page via Facebook Mobile App
1. Using your Facebook Mobile App
> Click Menu
2. Click Pages
3. Click your Facebook Page
4. Click Post Button
5. Type Something/Content to Share
> You may also include Link URL on your Post
> Your Post, by default is Public
> Finally, click the SHARE button
Related Topic:
You can find more information from Facebook Help Centre