Hi Neil and welcome to the Forum.
You didn't mention which Keyboard you have, but since you mentioned an SD card, I'll assume you have a KN7000 ??
What you wish to do is not possible, by directly using the files which are recorded to your SD Card. As you may know, your PC can play several types of 'Music' files - probably the most common being MIDI, MP3 and WAV files. Although the KN7000 can produce MIDI files, it is not a straightforward procedure - especially if you are, as you say, a beginner. Also, you would not be using the actual KN voices (Sounds) when playing back a MIDI file - the sounds would be produced by the sound generator circuits in the PC and would not be representative, of the wonderful sampled sounds in the KN.
That leaves two other possibilities - create a .WAV file, a or an MP3 file and then record them onto CD, since the created files are likely to be too large for a floppy disc. A rough rule of thumb for files sizes is about 10Mbytes per minute for a .WAV file and about 1Mbyte per minute for a MP3 file. As an alternative to a CD, there are now available, small memory modules, which plug into the USB port of your PC. They are available with capacities of 32, 64, 128 and 256Mbyte, so if your practise song is around 3 minutes in length and recorded in .WAV format, it should fit on a 32Mbyte unit.
To create these files, you can use the 'Audio Recorder' software, that came with the KN7000. The recording is done totally digitally via the USB ports on your KN and your PC.The easiest way to make the recording, is to first play your practice piece into the Sequencer and when you are satisfied with it, play the sequencer back as the source for your recording on the PC. Save the file to your PC hard disc, in the format of your choosing (WAV, MP3 or WMA) and then if you intend to use a memory module, then just copy the file to the module. If you wish to transfer to CD, then I would suggest the chosen file is recorded in WAV format, for best quality, using appropriate software such as NERO or Adaptec etc.
I suggest you read the available instruction manuals and if you have further questions, as I'm sure you will, post back on the forum.
[This message has been edited by Bill Norrie (edited 09-11-2003).]