I'm in Nigeria and I wish to travel to Canada to work. Can someone help me with the link up or agent or Canada government protocol to follow to apply for the working permit visa? I'm sponsoring myself.
You haven't specified what sort of job you'll be looking for, which makes it hard to give any more than generic advice. As with many countries, eligibility for work permits is strongly dependent on your specific training, skills and experience.
You should read carefully all the information on the official government site as well as their FAQ on work permits. There are many work visa scams, so please also read their information on common scams. No agent is necessary. No agent can guarantee you a work permit. If you are uncertain if an offer is genuine or not, please feel free to start a question here about it.
Most Canadian work permits require you to have a job offer from an employer. They will generally need a 'Labour Market Impact Assessment' (showing that they can't hire for that job locally) unless you fall into one of the exempt areas. There is a 'open work permit' which doesn't require an employer but this is generally for people already working in Canada who need to extend their work permit.
As well as the central immigration route, individual provinces have programs to encourage skilled workers to move to specific areas. Each province has specific requirements and job categories for nomination, which will depend on their needs. If you qualify through one of these programs, they can apparently be a quicker route.
Links to all the provincial websites can be found here.