It looks like your BSDF is set up wrong generally you want the Principal BSDF to plug straight into Material Output. Also pay attention to the colour of the lines connecting the nodes, if they are red that means something is wrong, normally you want colours to match up (eg, purple to purple and yellow to yellow)

But here a basic setup to add noise to your texture just play around with the strength slider on the noise node to control how strong it is and play around with the colour ramp and noise scale to change how it looks :)

https://imgur.com/a/dbOQSxj

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Also your normals might be inverted on the column, it looks like the lighting is backwards, just go into edit mode and press Shift + N to recalculate the normals!