Cannot figure out how to Add Up Formula Fields in CRM

Cannot figure out how to Add Up Formula Fields in CRM

Hello,
I created a few formula fields in Zoho CRM and wish to get the total sum of those formula fields.  This has proven very difficult to do.   I looked at the custom functions but do not understand how to implement them or what the property syntax is to achieve this outcome.

 I have spent hours just trying to accomplish something that should be so simple.  Does anyone have suggestions on how I can do this?