Hi everyone!
I basically wanted to know how to recognize from a music sheet if a song can be played in one of this melodeons.
Thanks !
Hello Daniel welcome.
If you have no musical theory at all, it will be helpful to get some. There is loads of stuff available on line and you will need some if you want to learn tunes from musical scores. The things you need are common in most instrument tutor's.
In direct answer to your question, in a score the key a it is in is shown by sharp (#) and flat(b) signs at the beginning of each bar.
At it's simplest:
Your box is in GC,
You have' a G major row on the outside. The key of G has one # symbol shown at the start of the bar. All tunes with one sharp can be played based on the outside row
You have a C major row on the inside. C major has no sharps or flats. If there are none in the key signature it can be played based on the inside row.
The other box is in Bb (two flats b b) and Eb (three flats bbb). A similar principle applies.
If you learn some theory you will find that it's very easy to change a score so that it matches the notes you have.
You will have some accidental notes. They let you play notes not in the main keys.
On the other hand, you don't have to have musical theory to play music. You may find it easier to just try to play tunes that you know by ear, starting with very simple ones.
Either way, you really need a teacher, though. It will make all the difference to how quickly you develop skills and how much you enjoy doing it.
[edit:cross posted with JohnAndy but, heigh ho]