The lights light up in two ways :
1) Just PLAYING either .NWC files from the Noteworthy viewer or .MID WIn media player or any midi sequencer just has the effect of lighting the notes up .
All that is happening is that the keyboard is reading MIDI IN ( via in this case your USB cable ) messages
2 A ) LOADING on the other hand means you used the SMF Casio program to select a midi file you might have downloaded from here. The SMF CONVERTER changes it to a STEP LESSON file
( " Dont worry about this unless youre trying to play other midis on your keybaord. "- Of couse I have set channels for EVERY .MID midi file here correctly so that it will. Not just any old format 0 midi files do this do this ) The right hand must be on channel 4 and the left hand on channel 3 )
2B) You should be LOADING to THE SONGS 65 to 69 and yep it will simply overwrite and put new ones .
( Is only using the smart card ( for which you need to load via a smart card reader) that you can store 200 songs simulataneouosly but I dont see the need - That is designed more for people going on GIGs etc or for whom its inconvenient to always have the usb pc CABLE CONNECTED )
"Raindrops"
here is a walk in the park with the STEP LESSONS as are many files
here and
hereAs |:Raindrops" rhythm is just simple consistent regular beats youd start directly witht the STEP 2 button ( STEP 1 button is just for rhythm) and when you are confident you press STEP button ( remember you can slow down the TEMPO to play both or one hand in time
Remember with step lessons play only the LEFT hand then only the RIGHT hand and only then BOTH Hands
Hope that helped

Mike