What are the ways to generate content from internal employees? Ways to make them content ambassadors & start a culture of sharing in the organization.

Put up contests. Contests are fun. But employees should be reminded about plagiarism and that the purpose of the contest is friendly competition and involvement in the growth of the company. 

of course since it is a contest, the winner should be awarded but not by money, by a merit or something else.

Another idea is to group them, randomly. Put up a contest on which group performs the best. The contest is something like "Team of the Month." Then for the next month new groups will be formed. This too, strengthens camaraderie.

Communication is the best thing to do so,but in a much informal way that will help the employees to express themselves freely.