How do I update a contacts task?

How do I update a contacts task?

I am trying to update a task for a particular contact, but cannot find a way to find the ID for the task.  I used get related record to find the task;
(zoho.crm.getRelatedRecords("Tasks","Leads",thisLeadID);

The map shows "ACTIVITYID", but it doesn't seem like I am able to use that that to update the task.

Anyone have any id how to the ID of this task?

Thanks