To move, rotate or scale the 3-D object first select it by clicking on it. You must be in pick mode rather than view mode.
You can quickly switch between pick and view mode by pressing the space bar.
When selected a collection of transform manipulators appears as shown below.
A selected Object with Manipulators
The X axis is coloured red.
The Y axis is coloured green.
The Z axis is coloured blue.
Moving the selected object
To move the object along an axis, hold the mouse cursor over either the red, green or blue straight lines and drag the mouse. The selected object will follow.
Rotating the selected object
To rotate the object around one of the axes click the left mouse button over either the red, green or blue circles and drag the mouse. The selected object will rotate about that axis.
Scaling the select object
To scale the object along an axis hold down the mouse over either the small red, blue or green boxes and then drag the mouse. The selected object will scale in that direction.