An overview of Luther's Reformation is given at this link as well as obtains other links to more resources on Reformation Day and its histories. 

Here are other resources on Luther's Reformation:

Reformation Day: Lutheran Celebration and Reformationbrötchen leads to The Lutheran Witness  where you can use the search icon to find more articles on this topic within the confines of this magazine company.

Reformation 500th Anniversary goes to the Lutheran Reformation 500th anniversary website done by the synod dedicated to this topic alone. It has many many resources even including a few children's resources. While this site was done for 2017, it still has a lot of great information.