If you are currently located overseas and would like to come to either Canada or the US to work, you will need to find an employer who is willing to sponsor you in order for you to obtain a legal work permit for that country. Employers on site who are open to assisting you with this process can be found under the "Work Eligibility" filter section on the job search page.
Keep in mind that not everyone on site is able to assist you in coming over, so be sure to only apply to those who are under that filter or mention it directly in their profile. This will save both you and other employers a lot of time so you are not communicating regarding an opportunity that is not a good match.