Its not very hard, really. Broadband is not like dial-up modems, where you just log in and you're off. From the computer's standpoint, you're on a network. Installing a network card is just like installing any other expansion card. It will connect to your network card via a RJ45 network wire.
Cable modems are quite simple.
It is best not to try using a splitter and running both a TV and your modem off of one cable jack. This weakens the signal considerably to your modem. In fact, your modem may just refuse to work at all, and may give you a blinking connection light meaning it thinks it is not connected at all. There are a couple ways around this. One is that you could install a signal amplifier onto the cable line.