This is what I've:

<VirtualHost 127.0.0.1>
   DocumentRoot D:\XAMPP\xampp\htdocs\mysites\tupega.com
   ServerName tupega.tld

    <IfModule mod_rewrite.c>  
    RewriteEngine on  
    RewriteRule ^/nuevoanuncio$ /create/nuevoanuncio.php    
    </IfModule>

    <IfModule mod_rewrite.c>  
    RewriteEngine on    
    RewriteRule ^/registrar$ /create/nuevousuario.php
    </IfModule> 
</VirtualHost>

Must i produce a new <IfModule> for each rewrite I want?

No, place the all of your rules in a single [cde] block:

<IfModule>

The <IfModule mod_rewrite.c> RewriteEngine on RewriteRule ^/nuevoanuncio$ /create/nuevoanuncio.php RewriteRule ^/registrar$ /create/nuevousuario.php </IfModule> block is just accustomed to avoid errors when mod_rewrite isn't available.