Sometimes, you'll have a collection of objects that you would like to manipulate as a element. For example, a collection of images. First, select them all, and then use the Group button on the Arrange Palette. Once grouped, PageCloud treats them as a single object and you can drag and resize them as a group.
If any of the inner objects had an aspect ratio fixed, like images do, then the aspect ratio of the group will automatically be enforced so you don't accidentally break the aspect ratio of the inner objects.
To make a quick edit to an object inside a group, you can double-click the object to temporarily make the group open, and select one of it's objects. You can now shift-click on other objects in the group if you like, to select them, and use the palette to edit them. When you click away from the group or hit escape, the group closes and your edit is complete.
You can nest groups, by first grouping one set of objects, and then grouping it again with others. To ungroup, select one or more groups, and use the Ungroup button on the Arrange Palette.
Note that if you change the visual style of a group object, such as a border or background color, those styles will be lost if you decide to ungroup - as the group itself actually disappears, and only the inner objects remain.