In Alberta, most employers not governed by the Canadian Human Rights Act can legally ask about criminal charges or convictions. Your best bet is to answer truthfully about your criminal record.
The most successful way to do this is face to face, so you can explain the circumstances.
If your criminal record is preventing you from getting work, you should consider applying for and obtaining a record suspension (previously known as a pardon). However, depending on your offence, you may have to wait to be eligible.
If you’re not asked about your criminal record, it’s up to you whether you mention it or not.
Here’s more information about Finding Work With a Criminal Record.