i have a trojan virus on my pc?

I have a trojan virus in my pc i was told bout a website that i could go too remove it for free but i dont know wat the website address is and i dont kow how to use it once there. I have found loads of websites but once on them i do not know how to get to the free downloads or the free removal programs i dont have credit or debit cards so i cant rgister with companies to get full versions and i cant really afford to go out and buy anti virus packages. please can someone give me some advice on wat i can do thankyou.