What to do in this step ?

Step 3: Upgrading the database

The update script for the database is located in

<eZ Publish root>/update/database/<mysql|postgresql>/4.4/dbupdate-4.3.0-to-4.4.0.sql

You can run this with the appropriate command line tool or application.

sorry for this
but from this u can at-least understand .how much this is important for me

Go to this link
http://doc.ez.no/eZ-Publish/Upgrading/Upgrading-to-4.4/Upgrading-from-4.3.x-to-4.4.x

tell me ,in which file i should do step no 2

For eZ OE 5.x and eZ JS Core you will need to replace the following rewrite rules when using Virtual Hosts:

RewriteRule ^/var/cache/texttoimage/.* - [L]
RewriteRule ^/var/[^/]+/cache/(texttoimage|public)/.* - [L]

with:

RewriteRule ^/var/([^/]+/)?cache/(texttoimage|public)/.* - [L]