Click on the link in the first message. Then read the directions. He says download and isntall progressbar from smustard.com and his plugin.
To "install" a plugin, if it is an .rb file, just drop it into your SketchUp "plugins" folder.
If it is a .zip file, extract it to your plugins folder keeping the same folder structure in place that exists inside the zip file.
Then restart SketchUp and it will work if you did it right.
Good luck,
Chris