How to re-write URL?

[ujjvalpandya]

Hi

I want to re-write my URL. I came cross two things :
1) .htaccess
2) <Directory> tag

Whichis best to use?
And i read abput both, but being new i am not able to get the thing. I read that .httpd.conf file should bt there in my machine to reqrite. But i serach the whole PC but didnt get that file. DO i have to install mod_rewrite. I have tomcate 6.0
I wnat to achieve following thing :

IF user enters the ....
http://localhost:8080/mySite/pgHome

it shoudl open the
http://localhost:8080/mySite/section=pgHome


What thing i have to write where? Which filter string i have to wrtie? Its urgent. Can anybody tell me? I am working in NetBeans. And after creating file where to keep it? and do i have to explicity install mod_rewite?

Thanks in advance.