@Nithin Just download any plugin and drop it on the mod folder which is located inside your elgg install.

You can hide the top bar. Go to views/default/page_elements/elgg_topbar.php and comment everything inside that file so that it  doesn't show anymore. That's what I did last time to put another navigation bar.

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Just for refreshing purposes. the mod folder today is where the index.php is lying.

Think, its a mod_rewrite/htaccess problem

USe this : http://docs.elgg.org/wiki/Install_XAMPP