Whenever I try using the xmp show html code it makes my page scroll until the code stops. How do I make it wrap like in the tutorials Lissa shows?

You could try putting the text in a table with a defined width. Also, you could use the codes &lt; (<) and &gt; (>) instead of the carets, which eliminates the need for the <xmp> tag. Finally, I think the <pre> tag works the same as <xmp>, but I'm not sure if that will make the text wrap with the page or not; it might be worth a try though. :)

That's just one of the characteristics of that tag. You could include the code in a scrolling div so that when it reaches the maximum width and height it adds a scrollbar. <div style="width: ##px; height: ##px; overflow: auto;">html codes</div>
The way Lissa does is like the one mentioned above, with &lt; etc
Or you could just use a textarea
http://www.lissaexplains.com/html5.shtml#textarea