In the previous exercises you were all students.  The teacher created a problem, you submitted the solution.  The teacher was able to look at the solutions.  

Now you are going to create a problem for your students,  and its solution.  You can't do that here.  you do not have permissions on this branch of the tree.    This area is only for submitting answers.  You have to use the main menu and click on "My Content."  That takes you to your area.    I presume that you are logged in. 

Then use the advanced tab to add a Skulpt assignment. 

You have 10 minutes to create an assignment.  The challenge is that you also have to create the solution to the assignment.   

So don't ask for something complex.  One student asked for fractals.  Do find a interesting command in the turtle documentation, and create a simple assignment. Ideally it should just teach one concept, and be independent of the other exercises.