Select Use grid library from the Grid Library submenu of the Grid menu to use a pattern from a grid library with the current crossword. This way you can use previously designed grids rather than editing the pattern of squares by hand.
Click on the grid library you want to use at the top of the window and then select one of the available patterns. If no patterns are listed then there are no available patterns for your current grid size. When you select a pattern it will display in the crossword. Click OK when you have selected the one you want to use.
If you cannot see all the grid behind the use pattern window you can click on the Minimize button at the top right of the window to minimize the window so that you can see all the grid.
You can delete or rename a pattern from the library by selecting an item from the right-click popup menu. You can also delete an entire grid library by selecting it and pressing Delete (but you cannot delete any of the supplied standard grid libraries).