and where can i found it?

I assume you're talking about the gun that turns up in lots of levels, not the Hoth-specific ones.

Look to the common\odf folder :

com_weap_gunturret.odf

It shows up in Zeroedit as a gun turret, and in the game as a buildzone that requires a pilot to construct it (friendly Jawas will also do this for yout team! )

Also in that folder, try


com_prop_barrier_02.odf

It's a barricade, again that has to be constructed by a pilot.

Ok,thx i found it. Now i only need to know how AI will use them.

I've had no problem getting the AI units to build them, but haven't seen an AI use the gun (though I've not looked closely, the gun wasn't the main focus of my test) A hint node maybe? Not sure, from the list in the documentation, but it's something I'll be trying out.

The pilot will build them but no AI use the guns.

Did you have any luck with this? I put two turrets near a CP, the pilots built them right away. When I attacked the CP, the bots jumped in the guns and blasted away. No plans/hubs/hints required.