Apple Macintosh PowerBook 145B - Manual (Page 55)

Drag
You drag an object on the screen by pointing to that object and
holding down a trackball button while you roll the trackball.
Practice dragging the startup hard disk icon and the Trash icon
around the Macintosh desktop. When you drag an icon, an outline
of the icon follows the pointer on the screen. When you release
the trackball button, the icon itself moves.
When you’re finished practicing, drag the icons back to their
original positions. Then click once in the middle of the desktop.
(Clicking anywhere outside a selected icon returns that icon to its
original “unselected” state.)
Chapter 2: Working on the Desktop 39