Asking for work sponsorship

Hi, my name is Ling and I'm 33 years old. My husband and I decided to apply for migration to Canada this year primarily because of our childrens educational and medical needs. I've attended a seminar in an agency to see our chances and they've told me that I must look for an employer who could give me work sponsorship. Definitely my family will be shouldering all the expences in processing our papers for migration but we really need an employer assuring that I will have a work awaiting to sustain the needs of my family once we get there. PLEASE HELP...help me to construct a letter requesting for a "work sponsorship". I am not that good in English and certainly doesn't have any idea what you write on to my letter...(a template will do)

I would appreciate any tips coming from your end. Thank you.