IP-Adress and DNS-Server change in OS X

Look for the WiFi symbol in the taskbar in the upper right corner and click on it. Choose Open Network Preferences...

In the new window choose Ethernet on the left hand side.

Afterwards you choose Manually from the drop-down menu Configure IPv4. You are now able to type in your specific IP-address, the subnet mask and the router. Router is also known as gateway or standardgateway. To add a DNS-Server click on the Button Advanced... and choose DNS above. By clicking on the + Button you can add a new DNS-Server.

To save simply click the OK button and all changes are applied.