Criminal "Expungement" is the process of going to court to ask a Judge to seal a criminal record. When a record is sealed, it does not show up in a criminal background check. It is important to remember that a sealed record is not destroyed. The police, immigration authorities, and other public officials may still see sealed court files for certain purposes.
Check out this flash video tutorial on how to fill out criminal expungement papers. You'll see how to start the petition, make copies of partially finished petitions, finish the petition, fill out the order form, fill out the affidavit of service, schedule your hearing, sign your petition, make copies of your completed petition, mail copies, file your original papers, what to do if the prosecutor objects, and finally, see what happens on your hearing day.
If you're not quite sure what an expungement is, check out the second video which let's you know exactly what it is, just click on the number two above.