Changing player's footsteps

[pogh10]

Hello I want to change the player's footsteps when they equip the item in nutscript. I looked up how to change the footsteps on the wiki, but there is only a function. I am pretty sure I shouldn't be putting a function inside of a function. I think I am supposed to use a hook but I am not sure how to do that. Below is the horribly wrong code:

ITEM:hook("Equip", function(item)
function GM:PlayerFootstep( ply, pos, foot, sound, volume, rf )
	ply:EmitSound( "NPC_Hunter.Footstep" ) -- Play the footsteps hunter is using
	return true -- Don't allow default footsteps
end
end)

[editline]5th July 2017[/editline]

I think I'm getting closer

ITEM:hook("Equip", function(item)
function ChangeStepSound(ply, vec, foot, sound, vol)
    ply:EmitSound( "npc/dog/dog_footstep_run1.wav" )
    return true
    end
hook.Add("PlayerFootstep", "ChangeStepSounds", ChangeStepSound)
end)

[editline]5th July 2017[/editline]

How I posted is how you do it.. Derp