where is the serotonin point in cew

I’m not sure what “CEW” refers to here, but if you mean the serotonin- producing area in the brain , it’s mainly in the raphe nuclei of the brainstem. Those neurons project widely through the brain and central nervous system.

If you meant serotonin in the body overall , most of it is found outside the brain , especially in the gastrointestinal tract ; one source says about 90% is stored in enterochromaffin cells in the gut.