This site explains the XHTML syntax very well.
http://www.w3schools.com/xhtml/xhtml_syntax.asp(The official W3C info is quite hard going.)One of the key things that catches people out with XHTML is that it is case sensitive so you can't use things like OnMouseOver, it has to be onmouseover. Both will work in the browser but the first would not be W3C standards compliant.You can use tables all you like but the recommendation is to only use tables for tabular data and CSS for any layout.It's quite hard at first to move from tables to CSS if you're used to using tables for layout but it's well worth learning. If you search for "tables to CSS" you should find plenty of tutorials. You basically replace each cell with a and then choose exactly where you want it and how you want it to behave.