In some cases, objects on your page are logically related to each other and should be treated as a single object. For example, if you have five rollover buttons in a row and you want them to stay aligned with each other, you should group them. Any two or more objects can be made into a group, but the objects must be on the same layer.
To group two or more objects
Select the objects you want to group together.
On the Arrange menu, click Group, or press CTRL+G.
If your objects are on more than one layer, you can still group them together, but you will first have to move them to a single layer.
To move objects to a single layer
Select an object.
On the Edit menu, click Cut.
In the Layers panel, select a layer, and then, from the Edit menu, click one of the following:
Paste in Front, or press CTRL+F, to paste the object at the front of the new layer.
Paste in Back, or press CTRL+B to paste the object at the back of the new layer.
For more information, see Copy and paste objects.