How can I get my criminal backgroung cleared if I did something 12 years ago?

Was it a misdeamer or a felony. Were you a minor at the time or a adult.

Assuming you were a adult, you have to make a motion with the court where the conviction happened, to have it explunged. It will take it off any public background check, It will always be available to police and national security background searches. But it would not show up for standard work background checks

A lot depends on what you did and how old you were. If you were a juvenile at the time then it's likely that your record has been expunged. If you weren't, you may still be able to apply to have the record sealed. However, a 12-year-old offense, unless it was a violent one, isn't likely to come back and "haunt you." It might affect your ability to get a job where you'd need to be bonded, but other than that it really shouldn't be much of a problem.