I don't actually know what they do exactly as I have never worked in a warehouse myself but I have known people, both men and women who have. I remember one man saying that it was not hard work where he was. They would pick out orders to go to certain stores and he said they had to stack up boxes of stuff on the truck but they were light items. In a warehouse you will have forklift drivers but not all of the people have to be able to do that. In a smaller business, they might allow anybody to drive the forklift but because they are not insured, it is a bit risky. It is pretty easy to get a forklift license and if the employer wants you to have one, they can ask you to take a course.
They would probably also need people to do the paperwork and make sure that all the items ordered ended up on the truck.
I have no idea what they make today. You can look at the job bank: http://www.jobbank.gc.ca/intro-eng.aspx for jobs and and to see what you have after taxes, punch in the yearly salary in this tax calculator: http://lsminsurance.ca/calculators/canada/income-tax
Don't just look for warehouse though. You may end up in an area where there are not a lot of warehouses but you can find something else that is well paid. The main thing is look at ads, apply and pick something you think will be easy for you and is relatively well paid.