Can a teacher search a list of courses and add themselves as a teacher to that course?
Jim, you've got two questions here:
Can a teacher search a list of courses?
If your school has created a custom list outside of Canvas, yes, but otherwise, teachers cannot search a list of courses in Canvas.
[Can a teacher] add themselves as a teacher to that course?
No. If your school has enabled self-enrollment (How do I enable self-enrollment in an account and allow students to self-enroll in a course?), and you have access to the course URL, you can enroll in the course as a student. There is no self-enrollment option for the teacher role.
If a teacher needs to be added to a course, he or she should contact the school's Canvas admin.
we will look at the APIs
Retrieving data ...