Did you try doing a search before you asked? This has been asked and answered several times.
Here's something I grabbed from one of the answers:
Bluetooth Internet Connection
It took forever, but I have the magical settings that will get a Windows 2000 PC connected to the Internet to share its connection over a Bluetooth-enabled Clie.
The following steps assume that:
1. You already have networking set up and can browse the Internet on your PC
2. You have installed all of the Bluetooth software for your USB dongle (I am using the DLink dongle)
Step 1: Ensure that both your LAN and Bluetooth connections are active (running).
Step 2: Enable connection sharing on your LAN card (the one hooked up to the Internet, NOT the Bluetooth one). This will give you a message about how the Bluetooth network address will be set to 192.168.0.1. This is fine. It doesn't matter if your home network is on 192.168.1.x. I am running this machine on DHCP right now, but my guess is that it doesn't make any difference if you are using static IPs. I'm going to try this at work tomorrow, so I'll post updates then.
Step 3: Configure your Bluetooth network. Make sure to specify the same DNS entries and gateway as your LAN network. This is the part that I kept messing up!
Step 4: Configure your Clie.
1. Make sure Bluetooth is enabled.
2. Make sure that your Clie is paired with the PC.
3. Now open up the Network settings and set the Service to Bluetooth, no user name or password, and the Connection is the Bluetooth Network.
4. Click on Details and set the Connection type to PPP, Idle timeout to whatever you want, and unselect DNS and IP Address.
5. Then enter 192.168.0.2 (or any other 192.168.0.x number other than 192.168.0.1, which is your PC) for the IP Address, and enter the same values for Primary and Secondary DNS as you set for both of your connections on your PC.
6. Click on Script and make sure that you have only one entry: End.
That's it! You may have to enable/disable the network connections on the PC and/or Clie before things get moving, but that is all there is to it.
Here is a Ping app for the Clie that was indispensible to me: