A Clipping Mask is not like a regular layer mask. What it does is, it takes a layer on top, and makes it into the shape of the layer below.
Basically, put a large image on a layer (say a texture), above a smaller image on a layer (lets say text). Right click, click on Create Clipping Mask, then the larger image, the texture, will only be shown on the text below. Giving you textured text.
The same applies to Splatter brushes and applied images (or anything else, really). Put the applied image above the brushing, create a clipping mask on the applied image, then move the applied image around.
(Excuse me if the last part is actually the other way around)