You have to meet all of the rules to qualify for the first-time homebuyer credit.
Go to the IRS gov web site and use the search box for first-time homebuyer credit.
You will have to file a 1040 income tax return along with the form 5405 for this purpose.
Because of the documentation requirements for claiming the credit, taxpayers who claim the credit on their 2009 tax return must file a paper --- not electronic --- return and attach Form 5405, First-Time Homebuyer Credit and Repayment of the Credit (see the instructions for help with the form), and a properly executed copy of a settlement statement used to complete the purchase.