When you start a new puzzle, the Bomb, Frame and Coach icons will appear below the puzzle, to the left and right of the tool selection buttons.
Tap an icon to use that item. You will be prompted to confirm that you want to use the item first. You can only use one item per puzzle.
The Bomb item fills in an area of the puzzle grid with the correct answers (filled squares or Xs). Usually this will give you enough clues to quickly fill in a large part of the puzzle.
The Frame item automatically fills in all the squares at the edges of the grid (i.e., the first and last row and column). This will give you enough information to quickly fill in a large part of the puzzle (see "2. Anchoring" in the Strategy Guide section for more information).
The Coach item highlights the next row or column where there is currently enough information (based on the clue label and any squares already filled on the line) to add more filled squares or Xs. Once all the squares that can currently be filled have been entered, the Coach will highlight another line where progress can be made. This continues until all the lines have been highlighted and the puzzle is completed.
If all the filled squares on a given line are entered in accordance with it's clue label, the Coach will add Xs to the gaps automatically before moving on to the next line. The Coach will not show the specific squares that can be updated at each step - you will need to apply the basic solving techniques (such as Simple Boxes and Free Space) to solve each line. (Please refer to the Strategy Guide section for more information.) While the Coach is active you can still interact with any of the other lines of the grid, and can continue solving the puzzle as normal if you don't need further assistance.
The number of Bombs, Frames and Coaches remaining are shown on their respective icons. At the start of the game you have three of each item available to use. If your stock of an item is depleted to zero, tapping its icon will allow you to purchase another pack of three in exchange for some Coins.
You can only use items before filling any squares on a new puzzle. If you have started playing a puzzle where you want to use an item, you will need to select 'Map View' from the Options menu, tap the puzzle on the grid, and select 'Start Over' to clear the grid.