Select the object to be aligned with the Pick Tool. Click the Arrange, Align and Distribute... menu. Click the Center of Page check box. OK. The object should jump to the exact centre of the page. Note that if multiple objects are selected they will each be aligned to the page centre. Create a group if you wish to align several objects to the page centre but preserve their relative alignment.
Uncheck the Vertical alignment checkbox to change only Horizontal alignment or the Horizontal checkbox to change only Vertical alignment.
The method used to select objects for alignment is important! If you drag the Pick Tool to define a rectangle outlining the objects to be aligned they will be aligned on the rearmost object. If you select each object in turn by holding the Shift key whilst clicking, the objects will be aligned on the last object selected.
Select the objects to be aligned with the Pick Tool. Click the Align button or use the Arrange|Align and Distribute... menu. Check the Vertical Center and Horizontal Center checkboxes. OK. In the example illustrated the Pentagon was selected first, the Rectangle second and the Circle last. The objects will be centred on the centre of the Circle.
Select the objects to be spaced with the Pick Tool. The illustration to the right shows three lines that need to be left aligned and spaced ate equal intervals vertically. For this example, in the Align and Distribute dialog check the Left checkox from the Align options and the Centre or Spacing checkbox from the Distribute options. OK.