Validate your site

Having progressed through the checklist to this point, I am a little unsure how to proceed. The W3C validator takes a single URL ... am I really expected to type in every possible URL from my site(s) to test every one? That seems awfully tedious.

I am also wondering where I find guidelines for what it is expecting and what to use instead. E.g., I have always used < br > as a solitary tag ... the odd man out in HTML where everything comes in pairs ... but the validator is complaining. Does this mean one should use < br/ > instead? I don't know that I have ever seen that. And, since the page I checked was the front page, it has a bit of special stuff from Full HTML in it like setting < font size="+2" color="#cc0033" > which got me three errors or < p align="left" to compensate for the top center content seeming to want to be centered. I get that one does this sort of thing with CSS preferrably, but this is one block on one page which for reasons not known to me doesn't display a title and doesn't format quad left like every other piece of content ... I could live without the color. Is there a reference?