When you download the controls package, you can navigate to the folder called ResourcesToInclude, which has several files in it. There is a text file called: Installation Instructions.txt, which reads:
Random Site Controls Installation Instructions
1) Copy the RandomSiteControls.dll to your project
2) Add in the Toolbox entries from the included ToolboxesConfig.config by either COPYING the entires into your own, or by adding them with the Sitefinity backend Settings UI at Settings->Advanced->Toolboxes->Toolboxes
3) Add in the virtual path entry as seen in "VirtualPathSettingsConfig.config"...again by copying the entry into your own, or using the backend UI located at Settings->Advanced->VirtualPathSettings->Virtual paths->Create New
4) Add this to the global.asax to register the section
protected void Application_Start(object sender, EventArgs e)
Telerik.Sitefinity.Abstractions.Bootstrapper.Initialized += new EventHandler<
void Bootstrapper_Initialized(object sender, Telerik.Sitefinity.Data.ExecutedEventArgs e)
5) Recompile your project, or recycle your App_Pool for the settings to take effect
To see the Widget and layout custom icons check the Theme folder in the zip file for the image and CSS. It's up to you where\how to load the CSS, and you might need to update the file to point to where you put the images too.
Please see the included videos to understand how the widgets work...should be straight forward.