Creating Seamless Tiles
First off, let me define a "seamless tile" for those of you coming here for curiousity's sake. A seamless tile is merely an image that repeating without a seam or an area in which you can tell the image is repeating. Tiling is used mainly when employing a complicated design or pattern for the background of a layout. Making these tiles seamless makes the layout considerably more professional-looking and overall more asthetically pleasing.
A Seamless Tile from Scratch
- Open a new image in Photoshop of about 100px by 100px. Any size will do, but I'll be using 100px by 100px. (File >> New)
- Create a new layer and fill it with the color of choice. I'm using #88c98e.
- Create a new layer for your initial design. Use any of the tools (Pen, Shape, Paintbrush, etc.) to create some sort of doodle drawing or basis for your pattern. Here's mine:

- Go to Filter >> Other >> Offset.
- Make the vertical and horizontal offset both 50px (half the height and width) and set the 'Undefined Areas' to Wrap Around. Click OK.
- Your image should spit into fourths and be at the corners with a small empty space in the middle, like this:

- Lastly, fill in the empty space as much as you like with more of the design to finish your seamless tile.
The Conclusion: When finished, set the image as a background image to any page and see how the tile flows seamlessly across the page. One very important note: When creating a tile with a different size starting canvas, be sure to set your vertical and horizontal offset to half the pixels in each perameter.