Sharing ADSL

Thanks first at you read my question and give me the answer. My name is Dominic. I’m from Malaysia – Johor.
I want to know about any software can use for share ADSL internet connection? Give me the example. I know we can use router to share internet, but in Malaysia, router is very expensive, not many users can buy it. So I want to know which program are suitable for share ADSL internet connection. Where can download it?