I am on OPT F1 status and my W-2 contains social security wages and taxes and medicare taxes for the year 2009. Which form should I fill to get a refund of my medicare and social security taxes and what does the social security and medicare wages mean? Do I need to add that to my normal wages?

On F1/OPT you are exempt from residency for 5-years. You must file non-resident tax return Form 1040NR or 1040NR-EZ and Form 8843. Your income is not subject to FICA taxes but you must pay federal and state income taxes.

On your OPT income you will get deduction based on tax treaty between the U.S. and your country.

Ask your employer to refund you the FICA (SS tax and Medicare) taxes. If the employer is not able to refund you, you can file Form 843 with IRS. File after about 2 months of filing your tax return.
Your U.S. Tax Return: U.S. Tax Filing Requirements for Non-Residents (http://taxipay.blogspot.com/2008/03/us-tax-filing-requirements-for-non.html)