code invalid according to W3C - dont know how to solve these

I have a rather big website, but it has 31 errors. I seriously dont know how to fix these.

any help on any error fix would be appreciated. Even some i dont know why it displays an error:

http://www.horecavacaturebank.nl

http://validator.w3.org/check?uri=http%3A%2F%2Fwww.horecavacaturebank.nl%2F&charset=%28detect+automatically%29&doctype=Inline&g开发者_如何学JAVAroup=1&user-agent=W3C_Validator%2F1.2

Thanks in advance!

my experience abt w3c validation, just read carefully and is tells itself what is problem, here in you page attributes used like rel are not what can say w3c not defined or permitted yet, one more simple error there used li tag but parent tag should be there either ul or ol. More to say is we have to validate when our design part completes, after code integration or session starts it doesn't works.