in the bags of wound markers there are black, white and brown colored markers, what are these different colors used for?
In the Rise of the Valkyrie Master Set, the black is a round marker used for tracking the rounds of scenarios in the manual (there's a little track for each one and you move the marker along it like a timer). The white marker is a grenade for the Airborne Elite figures (it should have a little decal of a grenade on the inside). The dark red (you may be calling them brown?) markers are the wound markers.
Later on, there were tannish-brown markers used for the "negation" power on a certain wave four expansion figure and for the same power on a glyph from the Swarm of the Marro Master Set.
There were also glow-in-the-dark markers from a werewolf in one of the Dungeons and Dragons expansions, and purple markers for Samurai in wave four. The very last D&D wave released had copper-colored Exoskeleton markers for the bug-like demon creatures in that wave.
There are bright red wound markers in the Marvel set. These act the same as the more muted red (brownish) markers in the regular sets.
So to sum up....
Black= Scenario Round Marker
White w/ Grenade Decal = Airborne Elite Grenade Special Power Marker
Deep Red OR Bright Red = Wound Marker
Tannish Brown = Negation Special Power Marker
Glow-in-the-Dark = Werewolf Lycanthropy Special Power Marker
Copper = Mezzodemon Warmonger Exoskeleton Special Power Marker
Purple = Samurai Bloodlust Special Power Marker