Newbie - I can't sing

http://chinesepod.com/lessons/i-cant-sing
 
A : 来，唱歌吧！
B : 对不起，我不会唱。
A : 没关系，随便唱！
B : 我真的不会唱。

A : Come on, sing!
B : Sorry, I can't sing.
A : It doesn't matter. Just sing anything.
B : I really can't sing.