Use the alignment grid to align objects as you place them.
To align objects along axes after you place them, select the objects you want to align and use the Align Objects pull-down menu ( ) on the toolbar or select Edit»Align Items. You can align an object along a horizontal axis using its top or bottom edge or its center point. You can align an object along a vertical axis using its left or right edge or its center point. The alignment option you select remains in effect until you change it. A dark border around the icon in the pull-down menu indicates the current alignment option.
Complete the following steps to align objects.
To repeat an alignment operation on another group of objects, press the <Ctrl-Shift-A> keys. (Mac OS X) Press the <Command-Shift-A> keys. (Linux) Press the <Alt-Shift-A> keys.
You also can select Edit»Align Items to repeat an alignment operation on another group of objects.