Please help us to help you by providing more info about your osTicket (version, webserver software, PHP version, etc.) and also writing your request in English would help a lot since not all of us can read/speak Spanish.
From the translation app of my (Windows) phone here a translation of your post:
Hello as I can do to assign tickets to a specific person , depending on what you select a filter , as my topic for help is Training and once selected the subject shows me the following
Area which is a filter
Date of application
Course name
And what I want is for you to select a filter option area the person who is assigned the selected area
Administrative example if I select the ticket was assigned to Maria
But if I select Trade the ticket was assigned to Paloma
Cheers