You should always put styles in an external stylesheet.
Then you could place this code into your HTML:
<section id="section-1"><iframe width="675" height="380" src="http://www.youtube.com/embed/hmAFhsxWhdY" frameborder="0" allowfullscreen></iframe></section>
<section id="section-2"><textarea rows="24" cols="25" id="desc" width="200" height="478">Text here</textarea></section>
And have something like this in your CSS file:
section {display:-moz-inline-stack;display:inline-block;vertical-align:top;zoom:1;*display:inline;}
#section-1 {width:680px; height:400px;} These are the ID's of your sections
#section-2 {width:200px; height:480px;}
Also if you are learning to use HTML5 elements you should make sure that you include the HTML5 shiv for older browsers.
Just pop this into the head tags of the HTML document.
<!--[if IE]>
<script src="http://html5shiv.googlecode.com/svn/trunk/html5.js"></script>
<![endif]-->