In Exam module: 
Topics in this video
1. Add a exam 
2. Assign Question in a exam 
3. Assign a exam to classes
4. Create a practice / Revision / Online test exam
Steps - 
1. Click "exam"
2. Click "New exam"

3. Or Update an existing exam
Notes -
1. You can't edit a exam if exam is already taken by students 
2. you need to publish an exam. students will see only published exams. 
3. Students can take revision and practice exam multiple times.