Question

How did the frog introduce herself and critisize the bird

Answer 1

the frog introduced himself as a music critic and told the nightingale that if she learned music(singing) from him, she would scale new heights. When he listened to the nightingale's sweet and melodious song he became too jealous of her. He criticized the nightingale's song by saying " your song must be your own". he indirectly wanted to say that the nightingale was copying somebody else's song.
hope this helps...

Answer 2

The frog introduced himself to the nightingle as he was the greatest musician in the bingle bog. He also told the bird that he often writes for the weekly magazine i.e the bog trumpet, where he writes his own songs and lyrics. He told the nightingle that with him she would reach great heights and will be able to be a perfectionist in music. The nightingle saw him as the great critique and thought as if he was Mozart, the great musician in disguise.
The frog critisized the nightingle by saying that the song which she sang last nigt was fine but it was too long and it lacked a certain force.