how to add button react native app.js

var tapSpeed = React.createClass({
  render: function() {
    return (
      <View style={styles.container}>
        <Text style={styles.welcome}>
          Tap me as fast as you can!
        </Text>
        <View style={styles.button}>
        !
        </View>
      </View>
    );
  }
});

var styles = StyleSheet.create({
  container: {
    flex: 1,
    justifyContent: 'center',
    alignItems: 'center',
    backgroundColor: '#FFCCCC'
  },
  welcome: {
    fontSize: 20,
    textAlign: 'center',
    margin: 10
  },
  button: {
    textAlign: 'center',
    color: '#ffffff',
    marginBottom: 7,
    border: 1px solid blue,
    borderRadius: 2px
  }
});