music manipulation

Score editors allow you to enter your notes, either from a MIDI keyboard or a computer keyboard and mouse, generally "carefully", i.e., one-by-one, and produce a nice-looking score and be able to play it, although you have to have an idea what such a score looks like and help it. There are many such editors; MuseScore is one of them, and is free. There are others that are not free -- Finale, Sibelius, etc (although some have limited free editions). There is no issue of "uploading" -- you do this on your machine. You can upload scores you make to web sites (such as musescore.com), allowing others to view them and play them, and, if you permit, download them. There are other programs that don't make scores, but just record what you play on a keyboard in strips looking like a piano-roll, and allow you to edit them. In any case, the more musical knowledge you have, the more likely you are to use these programs successfully.