Even if your all gung ho about getting to the Internet to meet some new, friendly people, talk about their culture, and then wipe them off the face of the earth in StarBlasters 3D Mega-Expansion Pack IV - Online!!!, you still need to do first things first. And the first thing is to get your LAN working. So, make like a Monopoly player and go straight back to section The Local Area Network, don't pass "Go," and don't waste your $200. If you don't have your local area network functioning among the computers inside your own house and between the computers and the router, then your chances of getting them all sharing an Internet connection are grim.
OK. Now, you've got your LAN a hummin' and all your computers are chatting like Aunt Patty at your last family reunion after she'd had four glasses of wine. Your kids just used the computer upstairs to print 100 pages of "Hi Daddy!" or "Hi Mommy!" or "Hi Parental Unit!" in great big letters in just the last 10 minutes to the printer in your office. Even the cat just sent a fax to PetsRUs. That's great! Now, it's time to move on to the next challenge - getting your Internet connection working, shared to all the devices on your LAN, and still keep everything as safe as possible. With any luck, this will turn out to be pretty anti-climactic in terms of effort as you've already done a good portion of the work.
Now, hold on there, hombre! You did read your Acceptable Use Policy as mentioned in the section Want to Host an Internet Game Server? Check First, right? Yeah, I know you skipped that section. It's OK. However, you really should check your ISP's policy on connecting multiple devices if you haven't already. Most ISPs don't care and many even will sell or rent you the equipment (they recommend) to help. Others say it's OK to hook up multiple devices if you pay them extra. Some just say, "No. One computer and one computer only." (Luckily, this position seems to be disappearing.)
Don't hope that you can clandestinely hook up your desktop PC, your laptop and your Xbox and the ISP will never know. Even if you are going through a router, which masks the devices on the other side, your ISP can tell if they choose to check. That said, most ISPs nowadays understand that a house with multiple computers, gaming consoles and other networked devices is just the way things are. They've learned to embrace it. (As in, they've learned they can make money on it by selling you upgraded packages with faster connections and equipment to support multiple computers and other devices like the Xbox and DVR.) Assuming this is not a stumbling block, let's move on.
In order to understand some of the things that will be done while setting up your broadband sharing network, it's important to have a basic understanding of how the Internet functions. There are a number of really good web sites with tons of information on the subjects introduced in the next few sections. This is intended to be really brief introduction with just enough information to help make sense of the tasks to be done here.
We need to digress a moment and talk briefly about how domain names and IP addresses work on the Internet. First, understand that the Internet operates on IP addresses like 121.22.47.219 rather than (domain) names like www.neatwebsite.com. People, however, have a terrible time remembering numbers, so a way was devised to equate a name to an IP address. When you open a web browser and go to the URL http://www.neatwebsite.com/, something interesting happens. Remember those Domain Name Servers (DNSs) that your router gets from your ISP (or that were explicitly given to you by your ISP)? The purpose of a DNS is to translate names like www.neatwebsite.com into an IP address your browser can use.
It's a lot like the process of looking up someone's name in the phone book; you translate a business' or person's name into a telephone number in order to connect to them by telephone. In DNS parlance, this is called "resolving" the name.
Your browser will consult one of your ISP's DNS servers and ask for the IP address that has been assigned to www.neatwebsite.com. The DNS server will respond with the IP address. Your browser will then make a request for a web page from the web server at that IP address. Every name you type into your browser's address bar must eventually resolve to a single, unique IP address. When the web server sends you back a web page, it sends it to the IP address that was included in the request. Just like the web server at www.neatwebsite.com, your (return) IP address must also be unique. Otherwise, there would be no clear path for the web page to find its way back to you.
So now you might be asking yourself why talking about DNS servers was important when the topic is supposed to be your router. (Go ahead. Ask yourself. We'll wait.) Recall that when we set up our internal network, we used IP addresses starting with 192.168. If you stop and think for a moment, thousands upon thousands of people may have purchased the same router that you did. Many of those people left the internal LAN network at its default settings (e.g., 192.168.0.1). That means that at any given moment there are probably thousands of devices connected to the Internet with their LAN IP address set to 192.168.0.1, 192.168.0.2, etc. Why don't web servers on the Internet get confused when trying to figure out which 192.168.0.2 to return a web page to? The answer is that servers on the public Internet never see or use those addresses.
IP addresses that start with 192.168 are special ones that are called "private" or "non-routable" IP addresses. What this means is that these addresses have been set aside for use by businesses and home users to use internally. You will never find a public web server at the URL http://192.168.0.1 for example. (You could, however, create your own internal "Intranet" web server at that address, and that's fine.) Likewise, the return IP address for the web page you requested would never be 192.168.0.2, for example. It will always be the IP address that your ISP assigned (temporarily or statically) to your router. All Internet data destined for all computers and other devices on your LAN, initially arrive at your router using that public, routeable IP address. It's up to the router to figure out which computer or other device attached to your LAN should receive the data (if any).