Networking can be a tricky business (that's why people spend 4 years doing a degree in it!), but once you are comfortable with computers on an application level, and you want to learn, you should be able to get some basic networks set up, without giving up 4 years of your life.
The most important thing with home networks is to keep them simple, it's very tempting to route/bridge/etc., but the more nodes/gateways/subnets you have in the network, the more that can go wrong, so keep it simple, as network nodes are very, very stupid (not so good at thinking outside the box).
Two final points:
a)Be methodical, you'll find you kick yourself less in the long run.
b)Ask for help, you're sure to know someone with more networking experience, swallow your pride and get the help you need, life's too short.
1. Check For Connection
Wired connections - ( i.e.Ethernet ) ports should have a link light to show that a device is at the other end of the connection and capable of transmission.
Wireless connections - you'll need to checking in your Wireless Network settings (Win XP - Start/Control Panel/Network Connections/Wireless Network Connections), to ensure there is a WiFi broadcast signal available, status should be "connected", and green bars should be showing.
If the network connection isn't showing, you more than likely have a device level problem, have a look in device manager (Win XP - Start/Control Panel/System/Hardware/Device Manager). Make sure the network adaptor you wish to use is there and operating (make sure also that there are no driver errors, a manual driver update will usually solve any driver issues, if you have the right driver....).
2.Check For IP Traffic
Wired connections - have a look first to see if you have data transfer (Win XP - Start/Control Panel/Network Connections/), find the icon for the Ethernet device that is physically connected, make sure it is enabled, then have a look to see if you have packets being sent and received through the device.
Wireless connections - Using the method above, you should be able to determine whether traffic is being sent over the network. If you have a connection, and you can't send packets, have a look to see if you are authorised to use the network. If encryption is switched on, make sure you have the right access key. Another possibility is that it's looking for you to use the same Wireless network SSID, it's usually set to "default", rarely an issue, but one to watch out for.
3.Check Your IP Address Configuration
The first thing to attempt if you're not connected, is if you can ping the node you are trying to connect to. Your product manual should tell you what the default IP address of the router is (if you don't know it already).
Note: In a perfect world we wouldn't have to worry about IP addresses, however, this is where most network issues arrive. 90% of the time, you won't even have to look at these, or know what they mean (you're not missing much). Win XP seems to be getting it's act together, so most network devices now tend to plug 'n play on the network level. This is achieved by having one node giving out IP addresses, running DHCP (Dynamic Host Control Protocol, if you must know), and every other device being allocated IP addresses from that node. Most networks default to the prime node (DHCP controller) being given the IP address 192.168.0.1, and all devices in the subnet being given similar address (in most cases just the last number in the address will change, i.e. devices will get 192.168.0.2, 192.168.0.3,192.168.0.4, etc.).
So, have a look at the IP address that your network device has (wired/wireless, they all need IP addresses), you'll find it by looking at the "support" tab of the connection status window.
In order to ping your router (there are other ways, but this is my way):
Open an MS-DOS prompt session:
(Win XP - Start/All programs/Accessories/Command prompt)
Enter the command:
This should give you a reply for each of the 4 packets sent.
If it doesn't, you'll need to have a look at your IP address configuration, If you'd like stick to the old school, you can do this in MS-DOS with:
This will give you the IP configuration of all network adaptors installed on your machine. Ideally you will see your intended device, it's IP Address, and it's Gateway IP address will be the IP address of the node you are trying to connect your machine to (In this example 192.168.0.1).
There are innumerable possibilities for error if this is not the case, so I'll simply tell you that you should:
1) Have ONE node running DHCP.
2) All devices should be set to "Obtain an IP Address automatically" (In Win XP - Start/Control Panel/Network Connections/Wireless Network Connections/Properties/TCP/IP Settings). Remove any rogue settings, DNS/Gateways/etc. that have been defined, you want everything blank.
As an alternative, use fixed IP addresses, but only if you have to, it's very unlikely that this will solve your problem. If all nodes are set up correctly it shouldn't make a difference.
4.Check you have internet connection sharing installed
If you can ping your gateway, it is WAN connected, and you still can't connect to the internet, the end is near.
Run through Windows network connection wizard, and make sure internet connection is switched on, this is more a problem with Win 95/98/2000, but it does come up occasionally. If you still have problems, it might also be worth having a look at your ADSL modem settings, sometimes idle fingers (children wanting to set up x-box live, etc.) will block traffic by changing NAT/port forwarding settings.
If you get this far, and you still can't connect, give your ISP a ring, they can see handshake attempts, etc. by your modem, so if they're worth their salt, they should be able to take you from here.
Hope this helps!