How birds fly

I wonder how birds fly!!!!!!

Is it only with the wings they have?

If so how?

The birds swings its wings up and down, it it pushes the air then it can only move up. But they are move both up as well as moving forward. How is it possible by moving the wings up and down and moving forwand the body?

Few days back i was on travel from tirunelveli to my native, nagercoil. When i was in the bus i was enjoying the beauty of nature. At that time a group of birds were flying. They were flying in the speed of the bus. How does this can happen? I agree that the wings helps them flying. But is it that the wings alone is responsible for the bird to fly? I want to find how birds fly and i will fly like a bird.