Hi!

I really need help.

I have a slave site that have the same template as the master site and now I want to change it but I can't understand HOW I do this???

I watched this tutorial:
tutorial.jms2win.info/joomla/multisite-1...ges-media/index.html

But it only show how to create a NEW slave site. If I follow this a just get a blank page and a possibility to make a new install.

To create a slave site with a specific templates directory, you have to create a JMS template rule and specific the action beside the "templates" directory that you want to copy it.
In this case this will copy all the directory into the deploy directory that you have assigned to the slave site.

Becarefull that this operation only works when you create the slave site.
Once a website has already creates "something" for a directory (link or physical directory) it will not be modified. So try to change Symbolic Link to copy will not change after the site is created.

So check if you have a physical directory or a link on the /"templates" directory.

See also the tutorial video 0.b slide 31 to 34 and in particular 34 that do the parallel between the different values to use.