1. Open a new square document
2. Draw/import icons and images (for this tutorial I'm using original images)
3. Arrange on the artboard
4. Select all objects, then go to Object > Pattern > Make to preview the pattern
5. Adjust the Tile Type
6. Fill in the spaces with extra images
7. Save Pattern
8. To create a PNG to use in web or print, create a new image
9. Select the pattern in "Swatches" and drag it onto the canvas
10. Adjust artboard to match bounding box
11. File > Save for Web, ensure "Clip to Artboard" is selected