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.