I don't think you can. Are you trying to keep track of your children's internet usage? Most volunteers here agree that additional software, external to the browser, is needed for that.

More info: Parental controls | How to | Firefox Help

Thank you jscher2000, I'm sorry to say this is an employee problem.

Boywaldo

Many business-level firewalls log requests by the IP address of the employee's computer. You may have a similar system, or you could install monitoring software. Depending on your company's location, this might already be allowed or you might have to give notice first.

As a former business owner of 30+ years, "employees" are just like children, except they don't smell as good and their toys don't fit in a toy box. Oh, and children don't get drunk after you give them their allowance! (yep, changed "pay day" to Friday so they have a weekend hangover)