I would like to start making my own background music. Can someone tell me how that is possible and also I will be doing this in the previous software (petit computer) - I don't know if there is any difference but just in case.

smilebasic or petit computer 3 has a wave thingy thats kinda difficult to use (at least to me anyway) but the sound quality is better i dont know about petit computer 2 and how it works

I don't know much about creating your own sounds, but writing music with pre-made stuff works just fine. You will have to learn MML - I think if you look at the manual (an electronic version should be with Petit Computer), it should tell you all of the coding things you need to know about MML.

For clarification, in Petit Computer you will want to look at chapter 10 in the help manual for information about how to write MML.

You might want to use Litterbox MML creator. Key:NDKJR3X3