At beginning this summary is a little embarrassing jajaja is not difficult like i did.
first check your sound card and you can see it with:
in your terminal.
in my case I have a mod hda, you can check the mod for your sound card in
at first you must set up on your mod hda in /boot/loader.conf like root:
with that your module for the sound card is on.
Then you need to set up your 5.1 channels, by default is 2.1 or you can put 7.1 stead of,.
In /etc/sysctl.conf like root, you do that. you have to add the line with your multichannel output audio system. in this link talks about this parameters:
Now just add this to 7.1 output multichannel audio:
to alter dynamically and see the results
if you need 5.1 you need to change 7.1 to 5.1 or take a sight to the link fore more information.
NOTE: The device.hint don't need to be altered, I erase every sentences added in /boot/device.hint.
Thanks to Fatmice for help!