If you have a valid job offer, be sure you answered "Yes" to the question "Does [your name] have a job offer in Canada?" This is found under the Work Experience form of your Express Entry profile.
Overview of the Express Entry system, how to fill out your online profile and how to apply for permanent residence.
An open work permit is a work permit that is not job-specific. Because it is not job-specific, you will not need the following when you apply for your work permit: