title: insert text to selected Textbox use Javascript
body: <p>I have 2 textBox and 1 button!
  I want to insert text to one of these textboxs. When I click to <code>textbox_1</code> and click button, mytext will appear at <code>textbox_1</code>. When I click to <code>textbox_2</code> and click button, mytext will appear at <code>textbox_2</code>.
  How can I do this by using JavaScript?
  Please help me! I'm new on JavaScript!</p>