Hi,
You need to learn how to use Ngui first. Ngui has some very specific conventions and rules.
ngui ONLY works with textures, so you need to create an image, then turn that into an atlas that you can then reference in a sprite, once you have that, you can start implementing playmaker and the ngui bridge to catch ngui events within playmaker.
Study the examples provided with the ngui playmaker bridge, its important that you understand how things work first.
bye,
Jean