Hi,
Co-op visa is a different visa, which international students need to get...if they have a co-op work term as part of their course. It is the only work permit for international students..where they can work full time (as part of the course..related to the course..paid or unpaid... basically to complete co-op/internship).
You cannot do regular..full time job... on co-op work visa, unless that is an internship/co-op part of your course.
You can apply for co-op visa..only if your course has a co-op work term/months, compulsorily as pert of the course to compelte it.
To work full time after graduation, you will need to apply for Post grad work permit(PGWP).
To know more:
http://www.cic.gc.ca/english/study/work-coop.asp