Step 2 ... I use the Alpha to selection tool in the layers toolbar (you can call the toolbar up by pressing F7). The way my templates are set up this will select the filled area on the highlighted layer.
Step 3 ... Select the base colour you want (no, the outfit on the go is not green).
Then use the bucket fill tool to fill the selection.
Step 4 ... In the 'Filters' menu, select 'Noise' then 'RGB Noise ...'
This brings up a separate box to adjust the settings of the noise
Just leaving the settings at the default values works nicely, but experiment with the settings and view in the preview window, when happy click okay and....
Voila
