Adding a new grid is simple. Just click on the plus symbol button and you'll be presented with a new screen to name the new grid. Add a title for the grid and click on the next button to proceed to the next screen where you can add items to the grid and configure how the grid will look on the front-end.
Once you've added a new grid, you can use the [fgrid] shortcode to display it on your site. You also need to pass a parameter id to the shortcode which is used to identify which grid needs to be displayed. You may also quick copy the shortcode along with it's ID to the clipboard by clicking on shortcode output panel from the grid editing screen.
Once the shortcode has been copied to clipboard, you can paste it inside your Post's or Page's content or widgets such as Text Widget or HTML widget and the grid will be automatically rendered on the frontend of your site.