So, as an instructor sometimes you need to create a grade column (like for in-class participation in a hybrid course) in Canvas. The only way to make another grading column is by creating a graded assignment of some sort. Here is how to do it:
1. Add your assignment (I prefer to do this from the module view)
2. Create a new assignment – in this example called “Midterm Participation Grade”
3. Set the points and set it to percentage (if you wish) and click on the submission type “No Submission”
4. Now it will show up in the gradebook and you wil be able to give a manual grade to the students.