To move an asset inside of Cascade, click on the asset you would like to move, then click on the Move/Rename tab. Find the Parent Folder option and click the browse icon. This will bring up a new chooser window. Browse to the folder where you would like to move the asset, then click confirm. Finally, click the submit button and the asset will move to it's new location.
Any links you have made to this asset will be automatically updated and the navigation will automatically place the asset in the new location.
You can move assets around by clicking and dragging assets in the Navigation pane. If you are dragging a file and hover over a folder, the folder will open.