You use the Align panel (Window > Align) and the align options in the Control panel to align or distribute selected objects along the axis you specify. You can use either the object edges or anchor points as the reference point.
The Align options are visible in the Control panel when an object is selected. If they do not appear, choose Align from the Control panel menu.
For a video on aligning and distributing objects, see www.adobe.com/go/vid0035.
To align or distribute relative to the bounding box of all selected objects, click the button for the type of alignment or distribution you want.
To align or distribute relative to one of the selected objects, click that object again (you don’t need to hold down Shift as you click this time). Then click the button for the type of alignment or distribution you want.
To align relative to a crop area, specify the crop
area you want to align to by selecting it with the Crop tool. Click
the Align To Crop Area button or
click the Align menu
and
choose Align To Crop Area. Then click the button for the type of
alignment you want.
To align relative to the artboard, click the Align
To Artboard button or
click the Align menu
and
choose Align To Artboard. Then click the button for the type of
alignment you want.