Website help for University work

[psp4lyf]

Hey guys,
Me and my mate are doing a group project where we have to create a rock ticekts website. He has made the website but we get errors when we check the site on validator

I have sorted some of the errors but theres still some I can not figure out. We have somethin like 160 errors now I have cut it down to 45, but can not get my head around the last few errors.

Can a member please help us out just solve the last few errors..
Thanks a hell of a lot in advance!!

[Invalid] Markup Validation of http://www.cse.dmu.ac.uk/~p11240731/imat/as/home.html - W3C Markup Validator

[Invalid] Markup Validation of http://www.cse.dmu.ac.uk/~p11240731/imat/as/information.html - W3C Markup Validator

[Invalid] Markup Validation of http://www.cse.dmu.ac.uk/~p11240731/imat/as/gallery.html - W3C Markup Validator

[Invalid] Markup Validation of http://www.cse.dmu.ac.uk/~p11240731/imat/as/tickets.html - W3C Markup Validator

[Invalid] Markup Validation of http://www.cse.dmu.ac.uk/~p11240731/imat/as/dummy.html - W3C Markup Validator

W3C CSS Validator results for http://www.cse.dmu.ac.uk/~p11240731/imat/as/firststylesheet.css (CSS level 2.1)