Have you indicated in iTunes what you want to have synced?
In iTunes under Devices (listed on the left side), select your iPad. You should see across the top of the iTunes screen, a list of tabs (Summary, Info, Apps...).
Click on each of the tabs and make your selections of what you want to have synced. Don't forget to click the Apply button at the bottom right corner of the screen to save your options. After you've made all of your selections, you can click the Sync button.