Is there any ways to use RUBY to build a dynamic website just like the way we use PHP? Till now, i only know about ROR framework which can be used to achieve that. But i wanted to write my own code and learn rather than rely on the framework.

Although I recommend learning the MVC paradigm for its own sake, it's possible to rig erb onto an Apache install and serve up vanilla rhtml files. Here's a tutorial (http://dekstop.de/weblog/2006/01/rhtml_on_osx_with_apache_and_erb/) I googled on how to configure things if you're using a Mac.