People are (usually) great at adding content to SharePoint.  They are not so great at telling anyone they did. There are 2 steps to SharePoint – add content, then tell someone about it.  People won’t know by magic.  How you do this can take place in a few ways :

• Manually email a (sexy) link
• Share content via the Share links
• Add alerts to everyone on new content
• Add approval workflow
• Assign tasks

Whatever the business process requires will determine how you tell people it’s there, but don’t forget that step.