how to insert multiple windows data by single click event

Write the code for all three of them under the same event:

void button_Click(object sender, RoutedEventArgs e) {
    saveDataOne();
    saveDataTwo();
    saveDataThree(); 
} 

This way, you can write more code under the same button handler. Perhaps, you may want to show us  the code that you are having or how you are doing it currently.