You can obtain a credit report at least once a year to check or correct errors or problems. The only official site for the free credit check is http://www.annualcreditreport.com. The report is free but actual scoring has a fee attached to it. You can check your report with the 3 major bureaus (Equifax, Transunion, and Experian) Be warned, your reports may not be identical, and if you do order a score, the system the lenders use to validate is slightly different from consumer purchased scores.
Remember, http://www.annualcreditreport.com is the ONLY guaranteed free site.