In that case you will need to qualify for a work permit on your own which won't necessarily be easy.
If you can secure a job offer from an employer in Canada as a registered nurse, then you can apply for a work permit without having your employer go through the LMIA process (because the registered nurse job falls under NAFTA). This is really your most realistic option for getting a work permit.
So the first step is to find an employer willing to hire you and support you in getting a work permit.