How to create auto populate field based on custom module in Zoho CRM?

How to create auto populate field based on custom module in Zoho CRM?

Hello, 

i'm still new to Zoho CRM and work as administrator in my company.
Currently, I'm configuring layout for Quotes Module.
So, the idea is, I've created a read-only field in Quotes called "Spec". I want this field automatically filled with Specification (came from Custom Module called "Specifications") based on Product that I choose.

for example :
I have data in Specifications Module like this :
Product : A
Specification :
  1. Spec 1
  2. Spec 2
  3. Spec 3

On the Quotes Module, when I choose A in the Product Field, the Spec Field will filled by :
  1. Spec 1
  2. Spec 2
  3. Spec 2

How can I do that? Please give me some advice.
Thank you in advanced.