Thank you for your question. The Canadian Library Association site has a good summary of the two programs which will prepare you for working in a library.

http://www.cla.ca/infonation/welcome.htm

You seem to be thinking of the library technician program. This will require you to apply to one of the library technician programs in Canada and begin your studies towards a two year Library Technician Program Diploma. The following link is to the Southern Alberta Institute of Technology, SAIT, site for their Library Information Technology program:

http://learnat.sait.ca/ict/lit-loa/

As your question is specific for working in a school library, please refer to the following site for the Canadian Association for School Libraries:

http://www.cla.ca/casl/literacyneeds.html

This site specifies that there are different kinds of work in a school library requiring different competencies.

"Teacher-librarian: A professional teacher with a minimum of two years of successful classroom experience and additional qualifications in the selection, management and utilization of learning resources, who manages the school library and works with other teachers to design and implement resource-based instructional programs.

Support staff: Under the direction of a teacher-librarian, may include graduates of a post-secondary library technician program who organize and maintain the resources and equipment and provide reference and technical support services to teachers and students; clerical staff who provide support services in areas such as acquisition, circulation, and processing of resources, shelving and filing of materials, and typing or word processing; adult and student volunteers."

The training you will require depends on what kind of work you want to do within the library. As you continue your research, take some time to explore the Canadian Library Association site and the diverse kinds of work in libraries.