ok - this means that you have a LAN connection either on your MOBO or as a plug in pci card - it is currently disabled but that can be fixed with a mouse click.
If you are going to go wireless broadband you will need a wireless router/modem with an ethernet connection so as to allow you to use your LAN connection (which is also an ethernet connection). The two black sockets you are referring to are I expect on your dial up modem - this becomes superfluous in the case of broadband. You will have another similar but slightly larger socket either on your mobo (have a look in the area of your USB sockets) or on a plug in card. This is what you need to use. If you buy a wireless router/modem you will almost certainly get a suitable ethernet cable with it. Does that help?