If you wish to transfer paintings directly into and out of the iPad you can transfer the files using iTunes
1/ Launch iTunes.
2/ Connect your iPad to your computer with the USB dock cable.
3/ Select your iPad from the Devices list in the iTunes Library column, then click the Apps tab.
4/ Now scroll to the bottom of the iTunes window to see the File Sharing area.
5/ Select 'ArtRage'. You will see a list of files appear in the right hand window. You can transfer files in and out of this folder. (These will be the original PTG files and any JPEGs or PNGs that you 'Exported to iTunes').