first off all, the site is a addon domain, and the the path is /home/USER/public_html/bborganico/
Is this your
public_html/.htaccess, or your
public_html/bborganico/.htaccess file? If the first one, I think you will have to include
/bborganico in the rewrite (both pattern (left) and replacement (right). If it's the second one, I think you can start with /categoria...
RewriteRule ^categoria/([0-9]+)/(.*).html$ /categoria.php?$categoria=$1&titulo=$2 [L]
looks mostly OK. Is that $categoria a typo? The "$" should not be there. If there is no RewriteCond before this, you can omit the [L]. Do you have
RewriteEngine On in the file? If this is in
public_html/bborganico/.htaccess, try
RewriteRule ^categoria/([0-9]+)/(.*)\.html$ /categoria.php?categoria=$1&titulo=$2
If this is in
public_html/.htaccess, try
RewriteRule ^bborganico/categoria/([0-9]+)/(.*)\.html$ /bborganico/categoria.php?categoria=$1&titulo=$2
Try
RewriteRule ^(.*)\.html$ /$1.php
Make sure you do it
after the other rule (categoria), so that you don't fail to match that rewrite. That will change .html to .php. If you also want to get rid of the "contenido/",
RewriteRule ^contenido/(.*)\.html$ /$1.php
should do it.
PD: i don't speak English, i speck Spanish
There is a board on this forum specifically for questions and answers in Spanish: Spanish Hosting Questions (Preguntas en Espa~nol). You might be more comfortable asking there, although your English is quite understandable.