Some of the error messages are cryptic. I do have plans to write a tutorial about interpreting the messages, but have not yet gotten to it.
Post your error messages and let's see if we can help.
BTW, many of the errors reported simply mean that the page's code does not meet the specification set by the DOCTYPE tag. It doesn't necessarily mean that the page is broken.
"Democracy is two wolves and a lamb voting on what to have for lunch. Liberty is a well-armed lamb contesting the vote." -- Benjamin Franklin