Once you’ve recieved the new addresses, you just need to bind them to your ethernet adapter.
kelani gave these nice clear instructions in another thread:
1. Start – Settings – Control Panel – doubleclick on Network Connections
2. Rightclick on Local Area Connection and choose Properties
3. Scroll down to Internet Profocol (TCP/IP) select it, and click Properties
4. Click the Advanced tab at the bottom right
5. You will see your current IP address. Click ADD and add the two IP addresses with the correct Subnet Mask provided with them.
6. Click OK to all windows, and the network service should restart. If not, reboot. They should be assigned after that.