There is only one item added with this mod, a paintbrush. It is located in the Tools tab of the creative menu.
To use the paintbrush, simply right click while pointing on a block. The block does not need to be in range, you can right click any block up to 256 blocks away. A gui will appear, where you can enter any URL. Enter an URL, and then click Paint, or slam your enter key.
Voilà! Your pixel art has spawned, centered horizontally from where you're pointing at, and going upwards. Simple as that!