@GTRHaw ...
You can absolutely do this...however, there are some limitations with the Free For Teacher (FFT) version of Canvas compared to a paid Canvas environment (which is what I assume your school is currently using). One of those limitations is the amount of storage space you have per course...which is 500 MB. This number cannot be changed. So, if your course is above that number, you're going to have to find ways of reducing the amount of content in your course so that it is below that number.
Take a look at the Comparison PDF file which is linked in the following document for the differences between FFT and a paid Canvas environment: Canvas Free-for-Teacher FAQ (canvaslms.com).
In your current school course, you'll want to export your entire course: How do I export a Canvas course?
In the FFT course, you'll use that export file to import the content. How do I import a Canvas course export package?
I hope this helps. Sing out if you have any other questions...thanks!