First you need to make sure you have ubuntu 14.04 LAMP server installed on your server .
Install GLPI on Ubuntu 14.04
Now you need to install GLPI using the following command
sudo apt-get install glpi
GLPI configuration provide database for this application select yes and preed enter
Mysql password for GLPI
Confirm Mysql password for GLPI
After the end of installation the following screen provides how to access GLPI
Now got to http://ubuntu-serverip/glpi and You should see similar to the following screen
By default glpi is having the following username and passwords to login
glpi/glpi for the administrator account
tech/tech for the technician account
normal for the normal account
post-only/post-only for the postonly account
Select glpi username and password to login in to the glpi with administrator permissions and you should see similar to the following screens.
Please check GLPI documentation how to use GLPI