1. Starting in the course platform, click on the "Modules" page on the left-hand side menu.
2. Scroll to the assignment you'd like to assign to only specific students or sections of your course.
3. Click on that assignment, and then select "Edit" from the upper right-hand side.
4. Scroll down to the "Assign" box.
5. In the "Assign to" field, remove "Everyone" and enter the name of a student or a section of your course.
Save, and you're set! Please note that all other students will be unable to access or submit this assignment, but you can use the +Add button at the bottom to assign to multiple students or groups with different due dates. For more information, see the article on due / availability dates.