Have a look at the WikiFormatting guide (you should have a copy of it in your Trac project):

http://trac.xp-dev.com/publictrac/wiki/WikiFormatting

In a nutshell, you would use one of the many wiki processors supported by Trac.

Adding colors is as simple as:

{{{
#!html
<h1 style="color: orange">This is raw HTML</h1>
}}}

Thnx i missed that page and i was looking at the “same” version on the original trac site (where for instance it doesn’t use #!hmtl).
I can use all of the processor that are listed in that page?
Since i can’t make the syntax higlighter to work ( i mean {{{#!python blablabla }}} ).
Finally, since i have to show some source code, i want at least to show the comments in green in the preformatted text block, but the html thing doesn’t work.

That example page uses the processors themselves, so, all of them should work.