The DOCTYPE is unfinished. You should be more specific with what kind of document you're giving the visitor 
Add in some meta tags as well to help your index on search sites.
http://www.w3schools.com/tags/tag_doctype.asp
http://www.w3schools.com/html/html_meta.asp
When you want to figure out what kind of doctype your page should be, use this table:
http://www.w3schools.com/tags/ref_html_dtd.asp
The doctype is correct for the page he is using. That is all you need for the the doctype of an html 5 page.
Anyway, there are some validation errors within your page, but they can easily be fixed as they are simple mistakes. You could maybe jazz the header up a bit by creating a graphic in photoshop or paint.net.
You may need to put a title for the page like so...
<titleTitle of page</title>Research up on typography will help you to make a better design as well. I can see you have different fonts selected but for only the body which is basically the whole of the page. Mix the fonts up a little, using serifs for headings and sans-serifs for content.
Not bad for a first website, but just keep practicing.