Hi Brent,
If you already have the course created, you can navigate to the People area of the course. You should see a +People button on the right hand side. The easiest way to add them is to copy/paste their e-mail addresses and then make sure in the dropdown you select the student role. Once you add them, this sends the invitation to join the course. Keep in mind that if you have not published the course, they will not receive the invitation until it has been published. If you do not see an option to add people or see the student role, you may not have permissions to add students to your course. In that case, you will have to reach out to the LMS administrator for assistance.
Here's the Canvas guide for adding users to a course: https://community.canvaslms.com/t5/Instructor-Guide/How-do-I-add-users-to-a-course/ta-p/1119