Errors W3C Validator

Could you please help me where I can find the file in which these errors for my site, and how can I fix them?

www.sugu.pl

You won't, all our sites are the same.

You will have to ignore this.

Although these fatal errors.

Invalid, which means the document (page) does not pass the standard for whatever DOCTYPE is set (in this case, XHTML 1.0 Transitional).

It's not that serious, and a lot of sites don't pass them, especially when there's a lot of dynamic content involved (like with Dolphin).  Go ahead, check some of the most popular sites around.  I strive to meet them, but only in a realistic sense.

 Nathan is correct.

Just check cnn.com.

I'd need to fix it

Existing topics on the subject.

http://www.boonex.com/forums/topic/W3C-Validity-.htm
http://www.boonex.com/forums/topic/w3c-validator-errors.htm
http://www.boonex.com/forums/topic/W3C-Validation-errors-.htm

All top sites i have checked all have errors. Regardless of the size of the company and how much money they can pour into the web development fund, their sites still don't validate. Basically it is not going to happen.

Its truly not something to worry about. Even if someone has free time he should play games instead of trying to fix this.