The extension warehouse was first included in sketchup 2013. In order to use it, open sketchup and go to Window---->Extension Warehouse. Sign with your google account and explore through wide arry of extension categories. You can also look for any particular extension. Afer discovering your favorite extension, just click on install option and abide by the instructions.

SketchUp and .rbz files: The SketchUp 8 and newerer versions will facilitate the users to set up zipped Ruby files (.rbz) and open it inside sketchup. If there is a standard (.zip) extension with the plugin, then the extension name can be modified from .zip to .rbz.

Go through the following processes to learn how to set up a SketchUp Ruby plugin script through the .rbz format:

• It is suggested that the users should log in their computer as an admin prior to set up any Ruby scripts as it will simplify the installation process and make sure that all the files are set up in the suitable places.
• Go to Window > Preferences (Windows) or SketchUp > Preferences (Mac OS X). The Preferences dialog box is displayed.
• Turn on Extensions. The Extensions panel will be visible.
• Select the Install Extension button. The Open dialog box is appear.
• Find the Ruby zip file to set up (.rbz).
• Select the Open button. The Ruby plugin will be shown in the extension lists.

*.rb files: In case you contains a file having the .rb extension, the plugin can be set up with the placement of the Ruby script file into the exact folder. After that restart SketchUp.

Windows - the default location for various sketchup versions will be as follow:

• SketchUp 2015:C:\Users\YOUR USERNAME\AppData\Roaming\SketchUp\SketchUp 2015\SketchUp\Plugins
• SketchUp 2014:C:\Users\YOUR USERNAME\AppData\Roaming\SketchUp\SketchUp 2014\SketchUp\Plugins
• SketchUp 2013: C:\Program Files\SketchUp\SketchUp ####\Plugins.
• SketchUp 8 and older: C:\Program Files\Google\Google SketchUp #\Plugins.

For Mac OS X - the default location will be as follow:

• Version 2013 and higher: Open a new Finder window, press and hold the Option key from the keyboard, then select Go in the menu bar> Library > Application Support > SketchUp # > SketchUp > Plugins
• Version 8 and earlier:[YOUR USER NAME]/Library/Application Support/Google SketchUp #/SketchUp/plugins

It is recommended to generate your plugins folder in the SketchUp folder by selecting File > New folder in your Finder window.

After reopening SketchUp, one will find that the script's commands are included with the proper menus. The script can also function through the Ruby Console (open the "Windows" menu, and then select Ruby Console).