Well you can. Setup a server of your own, install OpenERP/Odoo on it using the guides and invite the users in.

Installation is really pretty simple:

http://www.time-eater.net/?p=376

or official OpenERP docs:

https://doc.odoo.com/install/#installation-link

thank you very much.

please have you a link to freely download ubuntu 14.

thanks again

Here it is:http://www.ubuntu.com/download

Nevertheless, your question makes me think that you are newbie in Linux and adminting such server on the long term requires a minimum of knowledge.

You may like also to have a try with the windows installer of openerp: http://nightly.openerp.com/7.0/nightly/exe/openerp-allinone-setup-7.0-latest.exe

Franck

You can get unlimited free hosting of Odoo/OpenERP by translating this page and ordering :

http://openerp-online.fr/1-openerp-on-line-hebergement-gratuit.html

Nevertheless, if you need first level support, a paying hosting is better, for example :

http://openerp-online.fr/3-openerp-infogerance-vds-1ht-jour.html

and if your erp is strategic for you, I recommand you to contract Odoo support (for on-premises version) and apply it to your hosted solution.

Installing OpenERP/Odoo by yourself is not so complicated, but you expose yourself to mistakes if you are not familiar with system and database administration.