This "Universal" system applies mostly to the 3560-X and later. The classic 3560s largely stuck to the distinct image model (IP Base vs. IP Services) until the end of their support life (12.2(55)SE was the final widely recommended release for many).
If you need the web GUI, you must download the .tar file. If you only use CLI and are low on flash space, download the .bin file. cisco 3560 firmware download
To download and install firmware for a Cisco Catalyst 3560 series switch Go to product viewer dialog for this item. This "Universal" system applies mostly to the 3560-X