To select an object, click the object with the arrow. To select more than one object, drag a selection frame around the objects. To add an object to a selection, press Shift, and then click the object. The objects selected together can then be defined as a group, turning them into a single group object.
You can edit individual elements of a group. You can also delete elements from a group with CommandShift+click.
You can select single objects from a group by double-clicking, if you first disable the Double-click to edit Text icon on the Option bar.