I'm going to put Piano Marvel in with all the other online sites I've tried and say, NO WAY! I'm not even breaking into whether they work or not since that's not your question. I've been playing the scales like a crazy mental lately and when I run across problem "crosswalks" with fingering, accuracy, speed, I'm forced to concentrate on just four or five notes of a four-five octave run. During those intense concentrations, I've heard Chopin, Liszt, Beethoven, Bach...THAT is where these dudes got ALL of their inspiration: The Scales!
Composing, writing, all that, comes from within you, as your creativity. Therefore, no one can teach that to you. You can figure out how to become more creative by studying modern philosophy (Critical Thinking, it's called today). However, it's up to who you are and how much you care (passion) as to what comes of it.
My greatest suggestion is to LISTEN to the music you love and then ask:
"Why do I love it?", "What was on my mind when I was feeling xxx in that piece?", "How do I want my music to affect others?". You might choose to study "mood music", pieces written specifically for silent pictures. Name your very favorite composer and then, list all the reasons why their music is your favorite.
I know, I write too much. Summary:
1. Learn the major and minor scales and fall finger-first in love with them! Hours and hours and hours of scales.
2. Figure out what floats your boat and how to float other's boats using it.
3. Read music everyday. I don't mean play it. I mean "read" it, like a magazine.
4. Study Critical Thinking.