Thanks for your response.
I already have seen the permalink structure. I have something different. I have one news category template. Where i check if the id = 4 , then show a specific page content, else show different. And i have many links with different ids to come up on this page. Everything is done.
I only want to change the news-category/4/ to news-category/us-news/. Means my link should say something like http://www.mysite.com/news-category/us-news/ but by using htaccess, i will make it like news-category/4/ so everything works fine.
Let me know if you any query so i will try to explain it in more detail.