Although larger than the iPhone's display, the basic layout of the iPad's Home screen is the same: Icons for the installed apps are arranged in rows and columns, with four of the most used apps appearing in a "Dock" at the bottom of the main Home screen. As you install more apps, additional Home screens will appear to accommodate their icons; the Dock appears at the bottom of all of them.
The Dock on the iPhone and iPod touch accepts up to four app icons, but the iPad has a larger display and can accept up to six. To add apps to the iPad's Dock, press down on the icon of the desired app until all the app icons begin jiggling. Then drag the app icon to the Dock, and press the Home button when you're done.