Specific grouping in Tableau HeatMaps

Question

I would like to join an Excel dataset which contains:

• The name of a course
• The ID of a problem from this course (many pb per course)
• The ID of a user that has submitted an answer for this problem from this course
• the grade that the user has obtained at this pb from this course

What I try to achieve:

• Axe x : Every problem for each course
• Axe y : value of the grade (from 0 to 100)
• Axe z : Number of user for each Note value

So, if for the pb A of the Course A, the dispersion is like this:

• 9 users have 100
• 21 users have 80
• 40 users have 60
• 5 users have 40
• 10 users have 20
• 15 users have 0

I would like to have every value displayed on a bar and each value would be displayed by a square. Each square having a different color regarding the value represented. So, here, 60 would be darker than any other value (since the amount of people having this grade is the greatest) and 20 would be clearer than 0, 60, 80 & 100 but darker than 40 Then, just next to this bar, the same for the pb B & C. 

Answer 1

1. Move grade, name of a course, ID of a problem to Dimensions.
2. Put name of a course and ID of a problem on the columns.
3. Put grade on the rows.
4. Find a drop down list on the Marks tab and select Square.
5. Put COUNT(ID of a user) on the Color on the Marks tab