How do I right align div elements

Three elements—a button, a form, and a canvas—make up the body of my HTML document. The canvas should remain left-aligned while the button, form, and other elements are right-oriented. Here is the code I have so far; I want the form to follow directly after the button on the right with no space in between. The issue is that when I try to align the first two items, they no longer follow each other and instead are next to each other horizontally.

#cTask {
  background-color: lightgreen;
}

#button {
  position: relative;
  float: right;
}

#addEventForm {
  position: relative;
  float: right;
  border: 2px solid #003B62;
  font-family: verdana;
  background-color: #B5CFE0;
  padding-left: 10px;
}

<!DOCTYPE html>
<html lang="en">
<head>
  <script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.3.2/jquery.js"></script>
  <script type="text/javascript" src="timeline.js"></script>
  <link rel="stylesheet" href="master.css" type="text/css" media="screen" />
</head>

<body bgcolor="000" TEXT="FFFFFF">
  <div id="button">
    <button onclick="showForm()" type="button" id="cTask">
        Create Task
    </button>
  </div>
  <div id="addEventForm">
    <form>
      <p><label>Customer name: <input></label></p>
      <p><label>Telephone: <input type=tel></label></p>
      <p><label>E-mail address: <input type=email></label></p>
    </form>
  </div>
  <div>
    <canvas id="myBoard" width="600" height="600" style="background:lightgray;">
      <p>Your browser doesn't support canvas.</p>
    </canvas>
  </div>
</body>
</html>