Automatic Tiling will automatically create tiles automatically if your image is larger than your media. Automatic Tiling is the default setting for Tiles.  

Manual Tiling allows you to create your own tiles for an image. To use Manual Tiling, select Tiling from Image Tools, check Manual Tiling, and then click Setup. This opens the Manual Tiling dialog (Figure 2).

Manual Tiling allows you to select from the following options:

• Manual Tiles—Manual Tiles are tiles that you set yourself. You can set Manual Tiles by either dragging the tile boundaries to specific locations in your image or by inserting values into the Manual Tiles fields. To create more rows or columns of tiles, move your mouse to the edge of your image and drag the tile border onto your image. Use this option if you want to create tiles of varying sizes.
• By Size Tiles—By Size Tiles creates rows and columns of tiles that are of equal size. Use the up- and down-arrows to set row and column widths and heights. If your width or height is too large for your image, tiles will not appear. Use this option if you want to create only enough tiles to print an image larger than your media.
• By Tiles—By Tiles creates rows and columns of tiles that are evenly spaced across your image. Use the up- and down-arrows to set the number of rows and columns for your image. Use this option if you want to create an exact number of tiles of equal size.

TIP: You can learn more about the manual tiling tool by watching the Manual Tiling video tutorial

Overlap assists you when piecing tiles together by placing marks and other aids on your media. To use Tile Overlap, check the Enable Overlap option.   Overlap Size determines how much of the inside edge of your image will be repeated on sequential tiles. This allows you to join two tiles more precisely by giving you repeated portions of your image to match.   Zero-Line Marks places cross hairs on your image showing exactly where you need to place each tile to get a perfect match.   Dotted Overlap Marks show the boundaries of the tiles and help you place each tile.  You can determine the sides of your tiles that will get Dotted Overlap Marks by selecting the appropriate option.