First, we need to set the default SSID in the wireless Ethernet adapter to match the default SSID of the WAP in order for the Ethernet adapter to be able to communicate with the WAP for the rest of the configuration. If you purchased your WAP and Ethernet adapter from the same manufacturer and they are complimentary models, the SSID of the adapter may already be set to match the WAP's SSID. If this is so, you can skip to the next page.
We change the SSID used by the wireless Ethernet adapter using the software supplied by the adapter's manufacturer. (Windows XP [at least since service pack 1 or 2] and Vista also come with the Wireless Network Setup Wizard. However, I've always had better luck with the manufacturer's programs written for their hardware.) With the wireless Ethernet adapter installed and powered up, we launch the configuration utility. Every wireless adapter I've had seems to come with a radically different looking configuration utility - even for different wireless models from the same manufacturer. For this example, I'm using a Netgear WG511T 802.11G wireless Ethernet adapter. I also have the Linksys WPC54GS wireless Ethernet adapter, which has a very different looking utility, but with more or less, the same functionality. If the utility for your wireless adapter doesn't look like the screens shown here, don't fret about it. Just try to understand the purpose of what's being done, and you should be able to translate it to your configuration utility. Our goal here is just to make sure that the adapter is using the same SSID as the WAP.
The Netgear wireless utility for its wireless adapter - NETGEAR WGS511T Smart Configuration - has the ability to scan for wireless networks that are within range. If we didn't know (or forgot) the default SSID of the wireless access point, we could use this utility to find out. (However, our home WAP can be set to not broadcast its SSID, so this may not work.) In order to do that with the Smart Configuration utility, we open it and pick the Networks tab. Clicking on the Scan button starts a scan.
When the scan has completed, any networks found are displayed as shown below. This WAP is still set to its default values, namely an SSID of "NETGEAR" and no security. (The user's manual said the same thing, so this isn't much of a surprise.)
Now, we need to set our adapter to match the SSID of the WAP (if it's not already set to that value). The SSID setting for the WAP is the name of the network that it controls and needs to be the same for both the WAP and (all of) the wireless adapter(s). Once set for the Ethernet adapter, that SSID is the only network that it will pay attention to. If other wireless traffic from another SSID is broadcasting in the same area and on the same channel, both the WAP and wireless Ethernet adapters will ignore it. For the Netgear WGS511T, that SSID is changed on the Settings tab.
Above, I have set the name of the SSID to "NETGEAR" and I will save it in a profile named "Netgear." (Apparently, I wasn't feeling too inventive when I captured these screens.) Leave the security setting to "Disabled" (or change if to disabled if it isn't already) and hit the Apply button. (We will enable the security settings once we have established the basic wireless network. "Baby steps, Ellie, baby steps.") The result should be the screen picture below. That is, the Ethernet adapter should change from "Scanning" to displaying the new connection.
The status indicator line at the bottom of the screen now shows the wireless network we are connected to (NETGEAR), the channel being used (11), the current connection speed (54 Mbps at the moment, although this WAP and adapter card can go up to 108 Mbps), and the signal strength (8 of 8 dots or 100%; the WAP is just across the room from my laptop). I also clicked on the Save Profile button so I can recall this setup later if I need to. Using profiles comes in handy when we have a laptop that travels between wireless networks at home and work.
Note that we set the SSID, but we didn't set the channel. Most wireless Ethernet adapters will scan through the available channels and find the one your WAP is transmitting on. It will stop when it finds a WLAN that matches the SSID it is set to. If this does not happen, most cards will let you can set the channel manually. (This is left as an exercise for the reader.)
Now that the radio medium is established - the wireless equivalent of connecting the cable between the PC and the switch - we need to configure the Ethernet adapter to be on the same logical network as the WAP. That is, the adapter needs to have an IP address on the same network that the WAP operates its LAN and WLAN on. (However, it cannot be the exact IP address of the WAP; no two devices on the same network can share the same IP address.) Exactly what that IP address should be depends on the manufacturer (and possibly model) of your WAP. Assuming there is a router somewhere on your network - as will be the case if this is a combination router/switch/WAP - you may find that your newly-connected machine got a valid IP address using DHCP. DHCP is a topic for later discussion.
To make things simple and remove as many variables as possible, you may find it easier to set the address of the Ethernet adapter you are using (wired or wireless) manually to start with. It must be valid with respect to the WAP's default settings. For example, if the WAP uses 192.168.0.1 as its default LAN address, the manual setting for the adapter should be 192.168.0.xxx, where "xxx" can be any number between 2 and 254, inclusive. (You can't use 1 because the WAP has reserved that address for itself.) The manual that came with the WAP will tell you what the WAP's default LAN (a.k.a., inside, internal, local) IP address is by default. You will need to skip ahead to section Fixed/Static IP (Manual) IP Assignment in order to find out how to set the IP address manually, and then return here.