You can rename your iPad, iPhone or iPod by navigating to Settings > General > About. Tap the first line that reads "Name" to open the on-screen keyboard. You can then enter any name you want. Tap Done when you're finished.
You can also use your computer by connecting your device and opening iTunes. Click the Device button in the upper right corner, and double tap the Name line next to the picture of your device. Enter your new name and hit the Return to key when you are finished. Sync your device by tapping the Sync button on the bottom right corner of your screen.