I am new in Zoho CRM and not familiar with programming.  Please advise how to combine two fields and display the value into 3rd field.

e.g. 

Field One: xxx

Filed Two: zzz

Field Three: xxx-zzz

It is very easy and straight forward to be done in Zoho Creator.  (input."Field Three"=input."Field One" + "-" + input."Field Two").  How to make this in Zoho CRM? 

Thanks in advance!!