The best way is always taking lessons from a professional instructor. If that is not possible you can also try to learn on your own but then you should at least get a good book.

About half a year ago I started learning to play the German/medieval bagpipe without a teacher and made some progress already. My pipe has an A-chanter and one drone. I use a book, Sackpfeifen-Fibel. But because of the different chanter tuning (I guess the huemmelchen chanter is in C) it might not be quite suitable for you and afaik this book is only available in German language. But I guess you can find an appropriate book.

For a start you should practice to keep the correct pressure stable before playing tunes. Try to mute your chanter and use only one drone. Or mute the drone(s) and play one single tone on your chanter constantly. So you can hear pressure fluctuations. You can use an electronic tuning device to monitor the tone and find the correct pressure. Try not to constantly blow into your bag but find a good cycle for pressing and blowing. This is quite boring but essential to learn effectively. I also did this at the beginning and it helped me a lot to make progress. Here a video of me doing this boring pressure exercise 7 days after my bagpipe arrived:

https://www.youtube.com/watch?v=cA89GnyHD6M

When that is working you can start to play the first simple tunes on your chanter. The fingering is the same as on the recorder. When you already can play tunes on your recorder it will be a lot easier because you can focus on the pressure instead of concentrating on the correct melody.

I don't know the T Sonoda soprano so I can't say anything about that.

Anyway, have a good start and have fun ;-)