You can do this by converting the MP3 to mono WAV format on your computer and transferring to SD card but here is a quick and easy way to do it.
You will need an MP3 player or iPod or you could use your computer audio out. You will also need an appropriate cable.
You can record directly into the CD/MP3 input provided that you make the right settings but remember, the Spider Jam only records in mono and will mix down the stereo input internally.
Press and the RECORD SELECT button and make sure that MIXED WITH MICROPHONE is selected. Make sure that the MIC/AUX lettering under the button is lit - not GUITAR
So now, your Spider Jam is set up to record from your MP3 player.
When you are recording, you don't want any drums or backing tracks playing so, press the INPUTS/LEVEL button and make sure that the SONGS/DRUM control is turned off (fully anticlock).
Listen to your track playing through the amplifier and adjust the MP3's volume control so that it is as loud as possible without any distortion. There is also a way to set the level for the CD/MP3 channel if you press INPUT/LEVEL twice.
Now, you are ready to record. Just remember that there is a count-in when you press the REC button, 1-2-3-4. On the fifth beat, start your MP3 player.
When the song has finished, press STOP.
You can now save that backing track to internal or external (SD card) memory.
Internal memory will give you faster access to the track. You will also have the option to change the TEMPO/PITCH if you press the DRUMS/SONG button. This only affects the playback through the amp, not the recording, but is very useful for practicing tricky solos.
If you want to have a permanent pitch change, to better suit you vocal range, for instance, you will have to re-record the pitch-shifted track using the RCA sockets on the back. You can record into a computer, tape recorder or whatever recording device you have. If you want the pitch shifted track on your Spider Jam, just repeat the above process.