If you have a criminal record, don't lie about it; if they find out about your record, you could be fired and will be ineligible for unemployment benefits. In addition, lying about your record actually can be a crime in itself.
Explaining your criminal background history to a potential employer doesn't necessarily mean you will be denied the job. Try to emphasize how you've changed from when you committed the crime and stay positive. Also, make sure you have references that emphasize your character. Finally, be realistic about what kind of crimes can affect your ability to get certain jobs. It's best to be honest and prove how you've moved on and learned from your experience.
You can contact your state's Department of Justice for a copy of your record.
Please note: This page offers general legal information, not but not legal advice tailored for your specific legal situation. Rocket Lawyer Incorporated isn't a law firm or a substitute for one. For further information on this topic, you can Ask a Legal Pro.