How to Set Up Time Capsule With an Existing Network
The Apple Time Capsule is an external backup drive that includes a built-in wireless router. When connected to a DSL or cable modem, the router creates a wireless network for your home or office. During the Time Capsule's setup you have the option to create a new wireless network for the device or connect it to an existing network. As a safety precaution, the Time Capsule includes password protection to prevent users on your network from accessing your backed up files.
Plug the Time Capsule's power cord into an electrical outlet. Insert the other end into the power port on the back of the device.
Insert the Ethernet cable into the Ethernert port on the Time Capsule. Insert the other end of the cable into the wireless router.
Click "Go" at the top of the screen on your computer, then click "Utilities" in the pull-down menu. Double-click "AirPort Utility" to configure the Time Capsule.
Click "Continue" to set up the Time Capsule. Create a name for the device, then create a password. Re-enter the password in the verification field. Click "Continue."
Click the "I want Time Capsule to join my current network" option, then click "Continue." Leave the box next to "Enable guest network" unchecked if you do not want to create a separate network for users. Click "Continue."
Click the circle next to your Internet connection type, then click "Continue." Click "Yes" to allow the Time Machine application to back up your computer's data on Time Capsule. Click "Continue."
Read over the Time Capsule's setup summary. Click "Update" to finish the device's setup process. Click "Continue" to allow Time Capsule to restart and update the configuration settings, then click "Quit" to exit the AirPort Utility.