We need to establish whether your problem is because of something special about your work LAN, or whether you just need general help setting up the TCP/IP Control Panel.
When you say you can't connect to the internet, do you really mean that, or do you mean the WWW?
If it just WWW that is the problem, then as Davorin suggests, you may need to enter a proxy into your web browser prefs.
If there is no internet at all then your TCP/IP settings may need adjusting to suit the LAN (e.g. DHCP or static, Gateway address, Subnet mask)
Your LAN administrator should be able to provide this information.
If you don't know what to do with the info they provide, we can help.