Registering Visual Studio extensions is complicated process. For pre 2010 VS editions you need to copy appropriate files (.dll/.zip template/.regpkg...) into some folder and then write keys into registry with paths, settings, etc. (many, many keys).
These keys/settings are based on extension you are developing (LanguageService, Package, Add-in, ...)
After 2010 VS editions have new feature - .vsix extensions which is simple .zip archive containing all required files and registry keys.
You need to copy this .vsix file into some folder (recommended is inside VS install directory or other known folder as %VSInstallDir%\\) and then setup VS to load it (like running devenv.com /setup)
Read this blog for more info about discovering VS extensions: http://blogs.msdn.com/b/visualstudio/archive/2010/02/19/how-vsix-extensions-are-discovered-and-loaded-in-vs-2010.aspx