I am trying to make a photo like a water color.
The formula I am using has me
Apply filter->Dry Brush
Create New Layer
Add Layer mask
Then Edit->Fill->Use Pattern->Custom Pattern
However, under 'Custom Pattern' it says select 'Gouche Light on Watercolor' but this is not an option.
How do I get 'Gouche Light on Watercolor' to show up??
Aplying the Dry Brush filter and some pattern texture will not by themselves make a very convincing watercolour effect - remember too that there are watercolours made using transparent watercolour pigment and from opaque watercolour - like gouache. There are different watercolour looks as well - like wet on dry, dry on wet, and wet in wet. Watercolourists generally don't mix transparent and opaque painting. If you are going for a transparent effect you can make your own paper pattern to simulate Cold Press watercolour paper using the Reticulation filter and then applying the Soft Light Blend Mode to it.
There are a number of great tutorials online that can help you with this technique. I think this video shows a pretty convincing watercolor effect: