Hi,
Visit the website of the Excise and Customs dept. on
https://www.aces.gov.in and in it clink on the link of service tax and in it you will be ask for user id and password and then follow the process as mentioned in it.
Also there is a video tutorial on the said site, just go thru the same as it will be helpful in the same.
In case of any help do let us know as we are providing the return filing and consultancy services at very nominal rates.
Regards