Dropbox is a fantastic service that allows you to store files (2GB for free) online. It also syncs the files across all of the computers you own that have the Dropbox software installed, and, you can access all of your stored files via a web browser on any computer. For more info on the Dropbox service, see their overview or sign up here.
After you’ve signed up for Dropbox, you’ll need to install the Dropbox app on your iPad. It’s free, and can be found in the iTunes Store here.
You will also need to install iBooks on your iPad. The app is also free and can be found HERE. (Do you already have iBooks installed on your ipad?)
1. Lets get started. Add/ upload your new PDF file to your Dropbox account. Once the PDF has been uploaded, open up the Dropbox app on your iPad.

2. Tap the “Dropbox” button in the very upper-left corner of the app. Navigate through your Dropbox folders to locate the PDF file that you want to add to iBooks. Select it by tapping it once.

3. Depending on the size of the PDF (and your current Internet connection speed) it may take a while for the PDF to load.

4. Once it has loaded, tap the “Open with” button on the very upper right corner of the Dropbox app.

5. Select iBooks from whatever may be listed (will vary depending on which apps you have installed).