Steps to Create an Original Quiz Challenge
Scoring for Free-Text Questions
How to Create Other Types of Original Questions
Open Questions tab on Track Contents Manager.
Click + Add Question in the upper-right corner.

For Question Style, choose Free Text.

Enter a Title, compose the Question, and click OK.

If you add or update a Question that belongs to a Challenge already included in an Exam, be sure to replace that Challenge with its latest version. See Here
Currently, scoring is binary: points are awarded simply for whether something was entered or not.