How do I determine if I have an ethernet card or not. Also What's a Human Interface Device. Thanks in advance

In the device manager(right click my computer>>properties>>device manager), click the plus sign by Network adapters. There will be something there even if you don't have a NIC(ethernet card)... Dial up adapter and the AOL stuff will be listed there if you're using AOL. But if you have a NIC you will see something like 3com..., or Realtek..., or Linksys..., etc.. Alternatively, you can check the ports on the back of the computer. If one of them looks like it accepts an extra large telephone wire type connection into it, you most likely have a NIC. Human Interface Device=USB mouse or keyboard.

Or you could just look in the back of your computer, if there is a outlet that looks like a phone jack only bigger, then you have an NIC, if you see only one that looks like a phone jack and is the same size as a phone jack, you only have a modem.