Hi,
Congratulations on your permit!
If you are eligible to work in Canada but your study permit states you "may not work" or "may not accept employment", you'll need to amend your study permit to get the right wording in order to work. In the case where it is left blank or does not necessarily mention anything about being restricted from working, then you're fine.
Document checklist and amendment form can be viewed
here. [IMM 1436]
On page 2, leave all of Section B and question #1 in Section C.
In Section C question #2, write the following (as applicable):
Please amend my study permit to reflect my eligibility to work on and off campus in Canada so that I may apply for a Social Insurance Number. I am a full-time, degree-seeking student at the University of Windsor. Thank you.
Make sure you sign and date your application. It will be returned to you if it is not signed.
Upon completing the required documents and checklist, mail your documents to:
Temporary Resident Document Operation Support Centre (OSC)
Citizenship and Immigration Canada
Ottawa, Ontario, K1A 1L1
Processing times vary from 1 to 2 months.
Best of luck!