Selecting objects
To select an object in the edit area, just click on it. A selected object will be rendered with small "handles" and a black-and-white rubber band around it.
If you hold down the Alt key while clicking, the selection will toggle between the objects currently under the mouse pointer (if more than one).
Selecting multiple objects
If you hold down the Ctrl key while clicking, you are able to select several objects at the same time. Operations you perform, such as rotations and resize will be performed on all the selected objects as a group. You can also click and drag a selection with the select tool.
The individual selected objects are surrounded by the black and white rubber band, and the group of selected objects is surrounded by the handles.
In the timeline view, you may hold Shift to select ranges of objects.
Moving objects
The selected objects can be moved around freely by just dragging them around with the mouse. Finer adjustments (pixel by pixel) can be done with the arrow keys on the keyboard.
Holding down the Shift key while moving objects will lock the X position if you are moving it in the Y direction, and the Y position if you are moving it in the X direction.
Sizing objects
The small black handles around the selected objects can be used to resize them. The way the objects resize is dependent on which handle you use. If you hold down the Shift or Ctrl key while resizing, the objects will keep their aspect ratio (height-width-relationship). The size center can be moved if you hold down the Shift key while you drag it to the new position with the mouse.
Rotating objects
Objects can be rotated in an easy way. If you select the 
rotate tool or double-click on one of the selected objects, the handles will change appearance. Then the object(s) can be rotated freely around the rotate center (the small x with a round ring around it, in the middle of the selection).
The rotate center can be moved just by dragging it with the mouse. If you double-click on the rotate center, it will re-position itself to the center of the object.
Also see Rotating objects