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You can easily save files to your DropBox account from your iPad. All you need is a free DropBox account and GoodReader. GoodReader is a file management system for the iPad, and cost only US$0.99.
Most files on the iPad, including email attachments, can be opened in GoodReader. Once you have your file in GoodReader, select “Manage Files” on the right side of the app and select the file you want to move. Notice the options to Cut(Move) or Copy? Select the one you want.
Once you select the file you want to move, a green dot will appear next to the file name, and scissors will appear below the file name if you chose “Cut” instead of “Copy”:
Next you want to select “Connect to Servers” on the right side of the GoodReader app. Here you can connect GoodReader to your DropBox account.
Select DropBox, and the list of folders and files you have in your DropBox account will appear in a new window with an option to “Paste” at the bottom right of the new window:
Select “Paste” and the file you selected in GoodReader will be pasted in your DropBox account and available on the DropBox website and any device you have DropBox installed on.
The file then appears in your DropBox account: