Migrating to Canada from U.S as aregistered nurse

I.m a registered nurse both in U.K and in U.S. I'm interested in migrating to canada to settle with my husband. I have been advised to apply to the canadian embassy in the u.s for the skilled worker program. Do I need to secure employment in canada before I can apply for canada permanent resident through the canada embassy in U.S?. What is the process for securing employment with a reputable hospital that will be willing to offer you employment for the purpose of satisfing the requirements for the skilled labore program.? Is the canadian exam rigorious?. Would they accept transcripts already verified by the U.S nursing board?. Should I apply to the embassy while I go through the process of registration and employment at the same time?. I need help.