You should have two options for home sharing on your iPad - via the Remote app or through the Music App (the stock icon with the musical notes on it).
In the Remote app, in the upper left corner, should be an icon that looks like two boxes overlaying each other. If you press that icon, you should be taken to a screen that will show you your Apple TV icon and another icon for your iTunes library (mine has the big, round, blue musical note icon - the standard iTunes symbol). If you press that icon, you should then be connected to your home library.
This is, of course, assuming that (1) you've set up iTunes to home share and (2) iTunes is running.
In the Music app, if you press the "More" button at the bottom right of the main screen, you should get a pop-up window. One of the selections should be your home iTunes library. The two caveats about iTunes from the above paragraph also apply here.
Hope this helps.
Marilyn