You can add PDF (Portable Document Format) or ePub (Electronic Publication) books directly to your iTunes library and read them on your iPad. To transfer these files to your iPad follow these instructions:
1. Make sure you have the iBooks app installed on your iPad. You can find iBooks in the App Store for free.
2. Download the PDF or ePub files you wish to read to your computer, then run iTunes.
3. Navigate to File -> Add to Library. Find the PDF or ePub files you wish to add and select them.
4. From the left menu in iTunes (under LIBRARY) choose Books.
5. You should see all of the PDF and ePub files you've added to your library. Right-click (or control-click) on a file to Get Info.
6. Click the Options tab. Make sure the Media Kind is set to Book. If necessary, title and author information can be edited using the Info tab.
7. Connect your iPad to the computer. It should appear in the left menu under DEVICES.
8. Select your iPad and navigate to the Books tab. Check the box next to Sync Books. Choose All Books or select the individual PDF and ePub files to sync.
9. Click the sync button to copy the files to your iPad.
10. Run iBooks on your iPad. The Books and PDFs will now appear in your library.