C&C on lighting in this one

[tirediron]

...Is it correct to say digital images originally do not have noise, but develops them as an outcome of post processing...

No. Digital noise is a by-product of the increased power being consumed by the camera's sensor at higher ISOs manifesting itself as heat; this is exacerbated by post-processing, but is resident within the digital file from the moment of exposure. It's more prevelant on cheaper sensors, those with greater pixel density, and those shooting at higher ISOs because all of those require more power, which becomes more heat.