What shall I do to create a forum in my main website?

[eddielkk]

Suppose if I own a website to sell my products. And my site is hosted with geocities. Now I want to create a forum where my site members can discuss about the products in my website. What shall I do?
Shall I need to buy new domain for forum? Shall I need to again pay for hosting my forum? Or "Can I host it with geocities freely simply by uploading my forum scripts"?

I want to place this forum in my website home page with the link "Forum", and whenever the visitor clicks on the link, it should lead to the forum page.

First you have to purchase a domain hosting site, don't use those free hosting site. Then, you have to know what platform you want to build your forum. Normally, people ppbpb code for forum that strongly support mysql database. So, your hosting must support mysql database. After this, you can start to build your own forum with the code available.