I just installed Ubuntu onto my Dell Inspiron 1525 Laptop. I can use the internet when I have it wired, but I'd like to set up a wireless connection. When I right click on the Network Tools in the system>administration menu, but after that I have no idea what I have to do. All I have is my key that is the password to connect to the D-Link. But I don't know the username or any of the other details. Do I add to DSL or Wireless?
Please help if you can.

Do you even see a wireless option? Can you scan for any available networks? Your WLAN device might not even be detected by Linux.

A quick Google search suggests the 1525 uses a Broadcom chipset, which will probably require you load firmware before it will work.

There is a wireless option, but I do not know how to scan for available wireless networks.

Ubuntu has Broadcom drivers in the "restricted" repos.

Open the Synaptic package manager, go to Settings-->Repositories and enable the proprietary drivers selection.

Do you mean "left-click on System > Preferences > Network Connections"? If not, I would try that one

It is most likely under the "Wireless" tab. The only information I have added is the SSID (ie. name) of the router (in my case, "BTHomeHub-xxxx") and the key and key type under "Wireless Security".

I have found that wicd works much better than Ubuntu's network manager for scanning for and configuring available wireless networks. Wicd has a very easy to use GUI for configuring wireless networks.
Wicd conflicts with Ubuntu's network manager, so if you want to use wicd, you need to remove network manager. Just run these commands if you wish to try wicd:
Then launch wicd and scan for and setup your wireless.
If you ever wish to get rid of wicd and go back to network manager, just remove wicd and reinstall
network-manager and network-manager-gnome, and you will be right back to where you started with network manager.