If you wish to seek asylum status from outside of Canada, you will first need to be officially recognized as a refugee by UNHCR or a similar referral organization. Canada will not accept your application until this happens. Since you are from Rwanda, I expect it may be difficult to be recognized as a refugee since Rwanda is politically and economically very stable. Not wanting to return to Rwanda because you are concerned you won't be able to find a job there unfortunately isn't enough to be a refugee. However if you want to try, you can certainly contact UNHCR in Libya to see if they are willing to recognize you as a refugee.
You can find more information about claiming refugee status from outside of Canada here:
http://www.cic.gc.ca/english/refugees/outside/index.asp