Jim: fear not, if you know what your doing, it takes only minutes.
And to celebrate, a tad from W3.
Later. And now, for real, . . .
Later still: irony alert. When your site validates, the W3 people give you code you can use to show off this accomplishment. If you cut-n-paste as-is in a WordPress page, be sure to remove the paragraph tags, or the page won't validate. (WordPress adds its own paragraph tags, and duplicates are invalid.)