Are you allowed to work in Canada? Work Permits explained.
Some temporary workers do not need work permits to work in Canada – the list is as follows:
Athletes and coaches
Aviation accident or incident investigators
Civil aviation inspectors
Emergency service providers
Examiners and evaluators
Family members of foreign representatives
Foreign government officers
Health care students
Judges, referees and similar officials
News reporters, film and media crews
Students working on campus
Outside of these your employer may need to get a Labour Market Opinion (LMO) to hire you, you may also need a visitor visa - http://www.cic.gc.ca/english/visit/index.asp usually you have to apply for a work permit from outside of Canada, the length of time it takes and the ease of acquiring a permit depend on the type of work you wish to perform. More details about applying for a temporary permit can be found here - http://www.cic.gc.ca/english/work/apply-who-eligible.asp
For permanent workers or Federal Skilled Workers (FSW) are chosen as residents based on their skills, contribution to the economy and ability to settle in Canada. They are assessed on their language skills (French and English), education level, and work experience amongst other things. Currently the numbers of FSW per year is capped at 5,000 (Jan 2014).
To assess your eligibility please check out these pages - http://www.cic.gc.ca/english/immigrate/skilled/apply-who.asp and if you want to apply to become a FSW there is more information here - http://www.cic.gc.ca/english/immigrate/skilled/apply-how.asp