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Once the immersive UI is enabled, the immersive toolbar is displayed on the canvas. By default it will appear in the top left corner and it can be moved by left click-drag on the left edge of the toolbar.
Click the left edge of the toolbar and drag it to the centre of the Igloo canvas.
Select the Layers button on the toolbar and move the mouse over Layer2 to display the menu of layer actions. Press the Hide button. This will stop the Layer2 from being drawn on the canvas. Press the Hide button also for Layer1. The canvas will now be displaying the background image only.
Bring back the layers by press Show for Layer1 and Layer2 via the Layers button.
Edit mode
Press the Edit button just to the right of the Layers button. This will enter Edit mode and the currently selected layer will have resize handles drawn at each corner and along each edge.
Click on one of the handles and drag it so that the layer is reduced in size. Now click anywhere on the layer and drag it to a new position.
Click on another layer so that it becomes the selected layer. The resize handles will now be drawn on this layer instead. Try some more resizing and positioning and when completed press the Exit edit mode button.