replace an ip @ by a "normal" URL

[Ijlal EL HAZITI <ijlal.hzt@xxxxxxxxx>]

Hello everybody
I've just installed a webapp (sakai precisely) in a CentOs 6.2 server.
sakai is accessivle via @ip:8080/portal, and I need to replace that adresse by a normal URL: www.exapmle.com/sakai

I've already replaced:

#<VirtualHost *:80>
# ServerAdmin webmaster@xxxxxxxxxxxxxxxxxxxxxx
# DocumentRoot /www/docs/dummy-host.example.com
# ServerName dummy-host.example.com
# ErrorLog logs/dummy-host.example.com-error_log
# CustomLog logs/dummy-host.example.com-access_log common
#</VirtualHost>

by

<VirtualHost @ip:80>
ServerAdmin webmaster@xxxxxxxxxxxxxxx
DocumentRoot /www/cmcf
ServerName cmcf.men.gov.ma
ErrorLog logs/cmcf.men.gov.ma-error_log
CustomLog logs/cmcf.men.gov.ma-access_log common
</VirtualHost>

(I also tried <VirtualHost @ip:8080> since my webapp is accessible via @ip:8080/portal but in vain)
in the file: /etc/httpd/conf/httpd.conf but while retarting the httpd service, I get that error:

[root@cmcf ~]# service httpd restart
Arrêt de httpd :                                           [  OK  ]
Démarrage de httpd : Warning: DocumentRoot /www/cmcf does not exist
                                                           [  OK  ]

even if I've already created the "cmcf" directory in /var/www and gave it all required permissions.

I'll be pleased to get any of your suggestions.
Thank you