Add-in new PC in my network

I would like to add-in 1 new PC with Win98 into my network, using D-link
wireless router with 4 ports switch.Currently in my network have 2 PC, both
are in win XP. I didn't face any problem to configure into my network.

Now i want to add-in another PC with WIn 98 into my network, but i can't
configure it. I sent email to D-link support, they tell me to check the
adapter (NIC) IP configuration by type in "winipcfg" , but it just show the
PPP Adapter IP configuration in the dropdown list. I didn't the IP
configuration of the NIC adapter.

Is this causing by my network adapter can't communicate with my router?
How can i get my network adapter to communicate with the router?
How can the new PC get into my network and share the internet from the router?

Could anyone help me in this topic? Thank you very much.
my email address is (E-Mail Removed)