How add Custom Properties to armature?

Hello, y try add a custom properties with:

but when I try edit this property with:

bpy.ops.wm.properties_edit(data_path=“”, property=“NewProp”, value=“5”, min=0, max=10, description=“New”)

not work and appear a Runtime Error:

Traceback (most recent call last):
File “<blender_console>”, line 1, in <module>
File “C:\Program Files\Blender Foundation\Blender\2.75\scripts\modules\bpy\”, line 189, in call
ret = op_call(self.idname_py(), None, kw)
RuntimeError: Error: Direct execution not supported

My cuestion is How I should add property correctly? and edit that

to a single object:

obj = bpy.context.object
obj[‘myproperty’] = “hey”

to all objects
import bpy
from bpy.props import *

#see bpy.props for all avalaible property types.
bpy.types.Object.myproperty = IntProperty(default = 0)

If you want to add a property to the armature, not the armature object, do:

bpy.types.Armature.your_prop = bpy.props.IntProperty(min=0, max=10, default=5)