I've tried every method that I knows but didn't got the solution on "How to create an rss feeds and sitemap for a dynamic site that get updated automatically".

+1  A: 

The basic idea is to have your php file generate a valid RSS (xml) based on your database results. So, select the data you want to show from the MySQL db, and output them, conforming to the rss standard.

Check the top three google results

For the sitemap it will be a little harder, and it greatly depends on your structure, which is unknown to us. But the principle is the same - output a valid xml file conforming to the sitemap standard, based on the pages you want to show.