Where is your problem ?
It's REALLY very usual to reach an external server from most of networks ! For any networks, you need to know : the number of the network, the mask, the dns server and the gateway. For example :
- number of network : 192.168.10.0
- mask : 255.255.255.0 (or /24)
- dns server : 192.168.10.2 (exemple)
- gateway : 192.168.10.254
These 4 informations give : you could have 252-2=250 different hardware with ip address 192.168.10.45 for example. When a computer would reach any server outside the network, the trafic goes THRU the gateway which know how reach any others servers : this is 'basic routing'. (It could be a firewall ...)
It's really very small and basic knowledge about ip networks ...