Vhost or mod_rewrite or some other solution

I have shared space in hosting service. I installed worpress in same name folder under publi_html folder. Now when i added content or did any work, i worked off of http://www.mysitename.com/wordpress/wp-admin and all content is associated in the same way i.e., http://www.mysitename.com/wordpress/contentxyz. Now i have a domain name which i am using to point to this wordpress installation as http://www.domainnameiwant.com. Now i presumed that apache would redirect everything i posted under http://www.mysitename.com/wordpress/ as http://www.domainnameiwant.com/content. But that is not the case. What do i do to acheive this? I have read about mod_rewrite but dont know if that applies to my situation here. Pls help.