Thanks Thomas.
Let me show you what I have in my computer, see the attached pictures. Also, I don't understand what do you mean when you say remove the icon files in (BZ dir 14 ....images cad father). I guess that is the reason menu draw doesn't show bezier curves and I don't have a BesierSpline toolbar. Can you see the pictures and help me? Thanks.

Actually, this is an addendum to my previous question which should be disregarded because I was able to install BezierSpline to the folder plugins in the macintosh HD. I am posting a new question to the BezierSpline forum because after installing I cannot find the new controls on Sketchup8. Thanks.

Hello.
Jack here, new to Sketchup8, plugins, etc. I am designing a guitar and I would really appreciate your help with this and future questions, which are going to be my contribution since at the moment I don't have any answers.
I just downloaded the BezierSpline and installed it to the plugins folder on the macintosh HD so, my question is where is the location of the controls when I am in Sketchup8. Thanks.

I've downloaded the plugin and I've found it must to be put here: > Sketchup.find_support_file('Plugins')
/Library/Application Support/Google SketchUp 8/SketchUp/Plugins

But, I cannot figure out how to install the plugin I just downloaded to the place it should be put. Can you help me?

Hi all.
My name is Jack and I am designing a classical guitar using Sketchup8; because I am totally new to 3D designing I joined a Google group where I got the answer BezierSpline plugin would be useful to draw the arc profile as the one shown in the attached file. I must to be honest, I don't even know what a plugin is or how it works. Would you please be so nice and guide me on this; the plugin and the arc profile. Thanks!!