Funny (although the adjective "interesting" is more correct, in this case)

I have just started a new book, and it is very funny (or interesting). I'm learning about habits and lifestyle of American millionaires. I'm going to continue reading.

It's very important, especially for beginner, to write correctly, with the subject at the beginning of each sentence. You could skip the subject when you are talking with a friend in a very informal English.