Account suspended

Hi,

I am very new to wordpress but have two simple blogs in the go.

I was suspended from my host account for phishing.

They gave me the file name which was causing the trouble.
It was called atualizar.php

I do not know how it got into my account, but I traced the php file only to find it is in portuguese. I have askismet BTW.

I first thought the file got in through plugins, but I do not know.

Has anybody else had this problem. How do hacks get in, how do you track them down, how do you get rid of them, and how do you stop it happening again — in a way I can understand.

Many thanks if you can help me.

Gordon.