You would need to apply for jobs through reputable job sites or with employers directly and find an employer who is willing to give you a job offer. That employer will also need to obtain an approved LMIA before you can apply for a work permit.
It's generally very difficult to find employers who are willing to go through this process. There are also a lot of scams out there, so you need to be careful. If anyone asks you for money in exchange for a job, it's a scam.