Go to the Status tab in your router settings to see the DNS Server addresses you need.
The DHCP is on the first tab you come to (Set Up, basic set up). make sure this is Enabled. Click on the Static DHCP button to bring up the client list. Type in the first blank the numbers to use at the end of the PS3's IP address, enter the MAC Address in the next and check the box to enable this line. Then hit the Close button to save the changes.