如何使用我的表单包含附件文件到电子邮件？

I have a form:

我有一个表格:

<form id='contactus' action='send.php' method='post' enctype="multipart/form-data" accept-charset='UTF-8'>
<fieldset>
<legend>My Form</legend>
<table><tbody>
<tr valign="top">
<td nowrap="nowrap" style="text-align: right;"><label for='name' >Name: </label></td>
<td><input type='text' name='name' id='name' value=''/></td></tr>
<tr valign="top">
<td nowrap="nowrap" style="text-align: right;"><label for='email' >Email: </label></td>
<td><input type='text' name='email' id='email' value=''/></td></tr>
<tr valign="top">
<td nowrap="nowrap" style="text-align: right;"><label for='link' >Link: </label></td>
<td><input type='text' name='link' id='link' value=''/></td></tr>
<tr valign="top">
<td nowrap="nowrap" style="text-align: right;"><label for='subject' >Subject: </label> 
</td><td><input type='text' name='subject' id='subject' value=''/></td></tr>
<tr valign="top">
<td nowrap="nowrap" style="text-align: right;"><label for='description' >Description: 
</label></td>
<td><textarea rows="10" cols="50" name='description' id='description'></textarea>
</td></tr>
<tr valign="top">
<td nowrap="nowrap" style="text-align: right;"><label for='photo' >Photo: </label></td>
<td><input type="file" name='photo' id='photo' /></td></tr>
</tbody></table>
<td nowrap="nowrap" style="text-align: center;"><input type='submit' value='Send' /></td>
</fieldset>
</form>
<form id='contactus'