You have to use one of the following softwares (Music 2000 PS1 and MTVMG2 being the best IMHO):
-Music (Playstation 1, only available in Europe)
-Music 2000/MTV Music Generator (Playstation 1)
-Music 2000/MTV Music Generator (Windows)
-MTV Music Generator 2 (Playstation 2)
-Pocket Music (Game Boy Color)
-Pocket Music (Game Boy Advance)
-Music 2002 Club Edition (Windows)
-Music 3000/Funkmaster Flex's Digital Hitz Factory (Playstation 2)
-MTV Music Generator 3 (Playstation 2/Xbox. Both versions are identical)
Else, I guess that if you just want to showcase other people's track and not post your own music, then you can find music made with those softwares on Youtube or the two Facebook groups then post about it.