Validating my web site

Yesterday I had a lot of problems, one of the problems was that my html5 and CSS3 file was giving me problems when I validated the problem was that I used old HTML to do a horizontal line in the html5 file. The problem with the CSS3 I had like 5 errors which are fixed already but I still have one error which I cant fix.










 Now using html5 this is the right way to do it: