Well, that link is certainly low on the technical mumbo jumbo scale!
I'm not sure even I have the patience to wade through all of that.
Anyway, Kohdi, where does your setup stand at this point? Did your ISP / DSL provider do any installation services at all, or did they just deliver the hardware to you and wish you good luck?
It looks like your device has everything you need built in except for the ethernet switch, and you don't absolutely need that, since it is capable of operating with one computer connected to the ethernet port and the other connected to the USB port; (see p 13, section 5.4.3 of the manual). If you want to do that, you don't need to buy anything additional at all (assuming you have the complete kit that should have come with your modem).
Your package should have contained, in addition to the modem, an ethernet cable, a USB cable, a telephone cable, a power supply / brick for the modem, a quick start guide and a CD.
If you could tell me where you are in the process of getting connected, perhaps I can help you further.
Here is a link to the PDF user manual for your modem. This PDF document should also be on your CD that came with the modem.
If you are doing your own installation, don't forget to install the phone line filters on each actual telephone.
(Editted - found where ethernet and USB will work at the same time)