To assist you in initially learning how to accomplish some of the more complicated procedures, Service Builder shows an overlay on the window that visually guides you through the steps.
For example, when you first start to build a service template from the Flow tab, a helpful Getting Started Tips overlay shows how you can search for plug-ins, drag and drop a selected plug-in into the flow, and how to access the properties associated with the plug-in.
If you need it again, you can activate the hints by clicking the airplane icon (in the upper right of the Service Builder Edit window, when the Flow tab is selected).