HTML class kickin' me

My HTML class was a breeze until we got to XML, which I know absolutely nothing about. I keep trying to read the book and look up tutorials but it's pretty much all greek to me.

What I've managed to learn I used to try and do this homework, but I keep getting an error message. Can anyone tell me what's wrong with this?
<?xml version="1.0"?>
<?xml-stylesheet type="xsl" href="D:\Stuff\School\HTML\Project12\lab12-1solution.xsl"?>
<!DOCTYPE Video
[
<!ELEMENT Training-COurses (Adult-ed*)>
<!ELEMENT Adult-ed (CourseNumber) , (CourseName) , (CourseDescription)>
<!ELEMENT CourseNumber (#PCDATA)>
<!ELEMENT CourseName (#PCDATA)>
<!ELEMENT CourseDescription (#PCDATA)>

]

>

What I've managed to learn I used to try and do this homework, but I keep getting an error message. Can anyone tell me what's wrong with this?The type pseudo‐attribute in the xml-stylesheet processing instruction (PI) takes the MIME type of your style sheet as its value. The correct MIME type for an XSLT style sheet is application/xml. However, Internet Explorer only recognizes the nonstandard MIME type text/xsl, so you’ll probably have to use that instead. (xsl is an invalid value.)

XML documents are required to have a root element in order to be considered well‐formed. Video is, apparently, your root element, so you need to have <Video></Video> somewhere after the document type declaration.

If you’re going to use a DTD for validation purposes, then you need to make sure that all used elements and attributes are declared; the root element, Video, isn’t declared.