Programs|Teaching|Language. This will reveal a folder labelled SWI-Prolog. Open this folder and you will find the icon for the application. Double-clicking this will launch the program.
You should be rewarded by the appearance of a new window containing some welcome messages and the Prolog prompt |?- ,
which indicates that Prolog is ready for input.
You may find it convenient to create a shortcut to the Prolog application on your desktop.