Why isn't the modifier icon appearing when an object is selected? I'm brand new to Blender, and am attempting to subtract one object from another. Simple, I know, and all I have read says to use the modifier tool, which is a wrench.  However, I can not find this wrench.  

attached is a screen shot of my toolbar showing where I thought the wrench should be.

Can anyone please tell me what I am doing wrong?

I thank you kindly,
Matt
Metaball objects cannot have modifiers applied to them. Once an object that can have a modifier applied to it (like a mesh or a curve) is selected the wrench icon will appear.

Objects that can have modifiers added to them are:


Meshes
Curves
Surfaces
Text
Lattices