The question is very inaccurate (please see my comment to it above), so don't blame me if I answer wrong question.
So, if my assumptions are correct, read the above code sample. Basically, this is all you need to know:
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<input type="checkbox" id="checkbox"/>Check box<br/>
<textarea placeholder="Type some message here..." id="textarea" /><br/>
<input type="text" placeholder="Type one line..." id="text" /><br/>
<option value="Honda" selected="true">Honda</option>
<div id="placeholder" />
<!-- ... -->
(comment) brackets. Also, XML is case-sensitive, and XHTML attributes are all low-case. These differences creates problems in attempt to process HTML code as XHTML — it may be failed or render the code defunct.