I like this website for online HTML tutorials:
chrisk: not a bad example, but I’d avoid using the <u> tag: it is deprecated in HTML, and not even supported in strict XHTML. The justification is that elements should not be underlined unless they are hyperlinks, as underlined non-links tend to confuse users. 
Also, IMHO it’s preferable to use lowercase tag names in HTML. HTML allows you to use uppercase tag names if you want, but all tags must be lowercase in XHTML, so getting in the habit of just writing all tags in lowercase will save you the small effort of thinking about which case you can use if you also write pages using XHTML.