I assume you already have a full time job offer from an employer in Canada. If not, that's the first step.
If you do already have a full time job offer, the next step is for your employer to obtain an approved LMIA. This is something your employer must do (you cannot do it). The first step is for your employer to advertise the job for at least one full month to prove no Canadian could be found for the role. The next step is for your employer to apply for the LMIA and wait for the results. It can take anywhere from a few weeks to several months for the LMIA application to be processed. If the LMIA is approved, you can then apply for a work permit.
Your employer can find detailed information about the LMIA process here: http://www.esdc.gc.ca/en/foreign_workers/hire/median_wage/high/overview.page
