my favorite （刪掉music）star is wang leehom. i love him very much ，because（添加） he is not only Versatile(添加),but also a cool man(coolman 不是個單詞，要分開寫).
when he was twenty years old(當他還只有二十歲的時候)
he can play a varity of instrument very well.such as piano and violin（換下位置，violin沒有o，中間接and）
he is my idol.(他是我偶像)
i like his song "our song"(我們的歌）best可改為my Favorite(最喜歡的) song is "our song"
it is so great（已經都是個歌了就不需要了再說a song了） that make me vigorous（energetic是名詞，不能形容）.the song is mix up with hip-pop ，rock and so on(歌不能mix，所以不能作主語，得用詞組）.
he set a example for me that hard-working is the real key to success（這句很棒，用for好點）
I will always support him because he is my favorite star
我會永遠支持他，因為他是我最喜歡的明星
意思都表示得很明確，多用點復合句，效果會更好