For your information: thanks to your help I managed to install Sonar Home Studio (not the demo version) on my computer with Windows 10. I did the new installation NOT at 64 bits, but I could select the possibiltiy of installing at 32 bits. I also installed Big Fish and Rapture. Next, I installed the "old" VSC Sound Canvas" again (32 bits) and now Home Studio recognises it under the old name "Edirol VSC"! I also have Sonar LE installed, that works fine. So now, I have both Sonar LE AND Sonar Home Studio installed at Windows 10 32 bits. They both work with the "old" files!!! I am very happy. I can still play my old songs, and work on them, in both versions. As Home Studio now also works, I want to gradually move on to Home Studio, and use the newer possibilities. My problem with the old Sound Canvas has somehow solved (probably due to 32 bit installation , so I have only 2 questions left over for you:
 
1. Can you explain briefly the possibilities of Big Fish and Rapture?
2. Would upgrading to Sonar Platinum be worth the money?
 
Thanks again, I have learned a lot from this forum :-)

1- Big Fish is Loops, I don't use loops, I'm a musician and I make my own songs or use downloaded midi files which I edit to my taste. Loops are for people who are not musicians so they can build a song piece by piece. I think it's what is used in electronic and Hip hop. So if you are a traditional player you probably will never use them. 
If any use there might be drum lops I guess, but in the time it would take to dig through all that stuff I can have 3 songs finished :) 
Rapture is a powerful player that uses Samples to play sounds and just about every instrument is in there. 
This is why I say you will want to replace the old sounds as those are synthetic low resolution sounds. Nobody wants to listen to those anymore. 
We now use Sample libraries as those are real instruments and most sound very good.  
 
2-Not from the sounds of what you are doing. If your only working with MIDI HS has everything you need. The core program is the same in all versions. I would not send the $499 on Sonar as it's future is uncertain. 
 

@Cactus/Johnny, thanks a lot! You have been very helpful! I am going to work with this.
You are right, I don't use loops. I just record MIDI track by track, and then add the voices.
Rapture I am going to try. I guess this is a plug-in that I can load?
Thanks again.
 

Rapture is a Synth so you insert it from the list of instruments on the right in the browser. I haven't dug into too deep but it is full of high quality instruments. 
This was a $100 bonus as part of that deal. Home Studio didn't include much for synths compared to the full versions. So the free giveaway version was worth $150. Not bad.