I'm not wadmann, but here's how the script works:
create a few barrels on the map you want to explode once they take damage. Give them all a name (barrel1, barrel2, barrel3, barrel4)
now add (or create) the init.sqs in your mission folder:
barrellist=[barrel1, barrel2, barrel3, barrel4]
{_x addeventhandler [{hit},{_this exec {explode.sqs}}]} forEach barrellist
You see, just add all the barrels you want to script to run on in the barrellist.
now you only have to make sure the explode and burn scripts are in your mission folder too.
(little add, comment this line in explode.sqs:
;player sidechat format["%1",_dammage]
to get rid of the player side chat .
gl with this nice script!