To load soundbank into the A station, you'll first need the following software:
If you are on a PC, you'll need MIDI-OX (http://www.midiox.com/)
If you are on a Mac, you'll need SysEx Librarian (http://www.snoize.com/SysExLibrarian/)
Load the sound into the software, and send it to the A-station via a midi interface.
Once the soundbank is sent, it'll only be saved to the A-station's RAM, so to save it permanently, first, you need to check if memory protect is on or off. To do this go to 'Utility' mode, and check if the LED on the left (labelled porta/data) is on. If it is off, press the 'Unprotect/+' button to unprotect it. Next, go to 'Save' mode, make sure the LED light is on (which indicate memory is off), then press 'Write/+' to save a sound.