have you set up your hosts file . you need to open your hosts file ( both on server and client ) and add ( for instance ) :

oracleprod.oracle 195.154.125.147


Oracleprod => is your machine name
oracle => is your domain

at your browser type :

http://oracleprod.oracle:8000/

Port here depends on your type of installation , it might be 8000 or 8001

8000 is for production
8001 is for test

We usually use hosts file if there is no DNS on the network.

Good Luck