searching a job

Hi!
I am a Software engineer, From Nicaragua and I just wanted to know is it hard to get a job as a foreigner in Canada?(I do need a job to get a work permit), I searched for Jobs on different websites they are quite a few but, Is this the best way to search for a Job?

And Can I apply while I’m in Canada as a visitor or does it have to be in my country because if it’s the former I think it would be pretty much impossible. Thank you so much.