Are you putting exactly that? The system thinks that's an (x)html tag, you'll need to convert the angle brackets into their html characters.

< is &lt; and > is &gt;

Exactly what I want, but if write
&lt;this is a test&gt;
the string is disappear.
If this way:
&lt; this is a test &gt;
will show < This is a test >

How do I delete the space after the < sign ?
Thanks!

There shouldn't be a space if you dont put one. It might be an issue with your css. I don't know off the top of my head.

I try this way:
&lt;<code>this is a test</code>&gt;
just work. :)