Or you can visit following site of Income tax
http://incometaxindia.gov.in/
You can now file your returns online on the following site
http://www.incometaxindiaefiling.gov.in/portal/index.jsp
Here all you have to do is register your self with your PAN number. PAN number is compulsory as this is your unique user id. After you have created your login download the required form and fill up the form and generate a XML file from it and upload that XML on the site and your return filing is over.
The forms that are available are in PDF forms which you can fill it in any Adobe Acrobat Reader which is a free download.