If your parents sign a consent form and send it to DJP, you can be here at the age of 5.
IJP290, listen to these people. MIDI is entirley dependent on what the listener has on his computer. If you want to have some fun, download the trial version of Fruityloops, load the midi in there and export it to MP3.
Also, criticism is always gonna have negative aspects unless you are the best musician in the world. Do not be pretentious, you are 12, and you have a lot to learn. Deal with it. Learn, grow up, and get better.