There is no attribute "BACKGROUND"
… height="25" width="100% " background="http://www.mysite.com/te…
You have an element with a background attribute. No such attribute exists. So remove it.
This is an attribute (in bold)
It looks like you want to add a background image to an element. If the element doesn't already have an id attribute or class attribute, you can give it one and state the background image in the CSS stylesheet instead.
background: url(referencetheimage.png) 0 0 no-repeat;
is an example.
End tag for "TABLE" omitted, but its declaration does not permit this
You forgot to close a tag, or
you used something inside this tag that was not allowed, and the validator is complaining that the tag should be closed before such content can be allowed.
So did you find your </table> tag? Unless you've got lots and lots and lots of hairy code, you should be able to make sure that for every <table> tag, there's a </table> tag.
You can get this error also though if you did something like wrap a table in some inline element (like a span or an anchor). Those is no-nos.
3rd - Warning
Start tag was here
<table width="800" cellpadding="0" cellspacing="0" border="0" bgcolor="#F6F3DA">
Don't worry much about this error. When you fix error #2, it will also solve this error #3. What error #3 tells you is where to start counting your <table> tags so you know if you have enough </table> tags.