I am totally new at this! In inherited a HP Pavillion 6330 D6379A modem and would like to add the internet. Upon inserting the Yahoo disk, it stated I did not have a NIC, so I purchased one. How do I install the NIC. Trying to add a NIC to D6379A modem.

Hopefully the NIC came with instructions. If not, generally you just turn off the computer, open the case, insert the NIC in a convenient PCI slot, close the case, and boot up the PC. If Windows already has a driver for the NIC it will install it automatically. Otherwise you may have to run a setup routine from a disc provided with the NIC or d/l the applicable driver from the manufacturer's website. You should visit the website anyway to see if you have the latest driver version and d/l an owner's manual (if you don't have one). If the PC has an "onboard-NIC" there's one built into the motherboard itself and you don't need a separate NIC. An onboard-NIC may not have the latest bells and whistles so you can disable it from BIOS and install your own.

That PC has a NIC card but the original configuration of that machine only has like 48 MEG memory.

That PC has a NIC card .. No NIC card was ever included (other than fax/modem card) as far as HP own spec shows below. HP Pavilion PC Model 6330 - Product Specifications i_Xp/VistaUser

It appears this computer has a dial-up modem. What ISP do you have and how will you connect? Cable modem? Dial-up? DSL? And, what does the Yahoo CD have to do with anything? I'm also doubting you're running XP on this machine.. Are you sure that's correct? Life's more painless for the brainless.