Gohan photoshop

i downloaded a trial of photoshop CS2 today. i really want to take my drawings to the next level. i know this is a terrible coloring job but its the first time i've ever used photoshop. this picture of gohan is one i did a long time ago it was just uncolored. i didnt feel like drawing a new picture i wanted to try out the coloring right away anyways, any tips on using photoshop or things u observe through this picture please feel free to let me know i need all the help i can get.