To use this feature:
First you define or import a grouping of sizes. You can also save groupings of sizes for future use.
Then you select each group in turn and make the changes you want to the artwork for that group. For example, you might want to resize the artwork for a grouping of sizes, or change its location. The changes are displayed in the Design in Sizes pane snapshots for each size.
Finally, you save your file.
For more information, refer to: