Do u have to be a skilled worker in order to get a work permit?

I had applied skilled worker immigration and work permit 5 yrs ago, and yes, you have to be quite skillful to be qualified.
if you go to www.cic.gc.ca, and click "immigration", then "skilled worker", you should be able to find more details. there is a list of jobs that consider "skilled work", and if you have experience or education background for one of those on the list then you will be qualified.
but by listening from your question, if you have only been working as cashier, then I'm afraid your chance is pretty low.....

if you applied 2 years ago, then Canada's job market was really good and a lot of jobs have no one to work, then you would have very high chance.
but now since the economy gone down, the government has tighten everything, so it's even harder to get a work permit.

so I would suggest you better do more research and read thru the website before you apply, as it cost money to apply and if you got turn down because you are not qualified, you won't get your money back.

hope this helps.
good luck.

Not likely.Check out cic.gv.ca

Skilled workers have it easier, especially if their skill falls into an area where there is a shortage in Canada. But - you never know your luck. Why not apply and see what happens?