Oh okay sorry, I would try to explain myself better, I am trying to make a classification.
My dataset is a .grd file that integrates measurement Velocities (Vs30: Shear wave velocity of the first 30 meters) that were acquired in the field and a topographic model that estimates the Vs30 from the Slope of the relief https://earthquake.usgs.gov/data/vs30/, I have to integrate both datasets because field measurements have much more resolution than only the topographic model and Also the topographic model itself has more coverage in extension but lower resolution, I have achieved this task, with the Surface command. The generation of an integrated .grd that would include field measurement and the topographic model.
The next step is to study the velocities which I did with the Histogram command and establish ranges that would correspond to classes (from the image above the first one I have published ) I have built 4 classes using the integrated grid of Vs30 (field measurements + topographic approx)
Now I have the ranges for the classes and I need to separate those classes and give One Color to each class so my map represent discrete areas of the Velocities rather than a continuum variation, this means that my map should have 4 colours one for each class
and with these areas or this new grid with 4 classes, I will build polygons.
I hope I have made my best explaining what I am trying to achieve. I am sorry if I confuse you guys. and Thank you for your support.
K