Lou,
After my less than successful tutorial attempt on clone stamping that you already knew I thought I better start out simple and you can tell me from there how far you want the volume turned up so to speak
This is as simple as it gets so apologies in advance:
New document with a black background
New layer
Select a circle and fill with what ever colour
Click and drag on the layer on to layer mask and hey presto
I said it would be simple but I needed some sort of starting point to work out where you are at

Plus it's been a while since I've worked on the advance stuff so I need the time to practice
Here is an example of a mask I did ages ago took about 4 hours to get it right, for the life of me I can't find the psd

only the jpegs

If i can find it I'll mail it too you for a look
Not my photo btw
Before:

After the mask and everything else was applied:
