Images will be cut on your material according to where they appear on the screen. The placement will also depend on the Orientation selected in the Page tools options.
You are able to view on screen where a resulting cut will be made on your material when using the cutting mat by doing the following:
Go to the Page tools option
Select the Reveal Cutting Mat option
NOTE: This will allow you to see exactly where your images will be cut according to the actual grid on the cutting mat itself
If desired, you may select to have this always shown by doing the following:
Go to the File menu (PC) or Silhouette Studio menu (Mac)
Select Show Always for the option under "When Using the Cutting Mat"