Using canvases
The canvas is your work area, where you create, edit, and move objects. Any document contains at least one canvas, and you can create as many as you like (and thus have as many separate work areas as you like) in the same document.
The Canvases sidebar
The canvases in your document are listed in the canvases sidebar. To open it, select Canvases from the View menu or click the Canvases toolbar button. Each canvas has a title, a disclosure triangle for showing its layers, and a preview image.
To select a canvas, click its name or preview. The canvas appears in the document window, where you can add and edit objects.
To rename a canvas, double-click its name in the sidebar.
To create a new canvas, click the new canvas button at the bottom of the sidebar. 
To delete a canvas, select it and then press the Delete key or choose Delete Canvas from the Action pop-up menu at the bottom of the sidebar. Any document needs at least one canvas, so you can't delete the last one.
Canvases can be dragged around to rearrange their order, or to copy them between documents.
To change the style attributes of a canvas, first click its preview in the sidebar; it becomes highlighted in color rather than in gray to show that you are now working in the sidebar rather than the main canvas area. While the canvas is highlighted in color, use the Fill inspector, Lines and Shapes inspector, and Image inspector to change its style.
To change other attributes of the currently selected canvas, like size, units, grid, or automatic layout, whether you're working in the canvas sidebar or not, use the Canvas Size inspector, Grid inspector, and Diagram Layout inspector.