Creating a task, i can not work out how to get ID for What_Id

Creating a task, i can not work out how to get ID for What_Id


hi

From Module A function I map Module B record reference membershipid (ours).

I need Module B Zoho ID to create the related to on task. 

All examples i've seen start with the Zoho ID. 

void automation.LTM_Assign_Dispute_Task(String membershipid)
{
try 
{
membershipid = input.membershipid;
info membershipid;
// DOES NOT WORK - 03/02 GT
// ===== Input: Account ID =====
// This could come from a workflow trigger or parameter
membership_details = zoho.crm.getRecordById("Pro_Memberships", membershipid);

// ===== Step 1: Fetch related Contacts =====
// Check if related records exist
if(membership_details.isEmpty() == false)
{
zcrm = ifnull(membership_details.get("id"),"");
info zcrm;
// ===== Step 2: Prepare Task data =====
taskMap = Map();
taskMap.put("Subject","Membership: Disputed Payment");
taskMap.put("Due_Date",zoho.currentdate.addDay(7));
// 7 days from today
taskMap.put("What_Id","7568480000xxx7742");
// Related to Account
taskMap.put("Status","Not Started");
taskMap.put("Owner",ifnull(membership_details.get("Owner"),"").get("id"));
taskMap.put("$se_module","Pro_Memberships");
// ===== Step 3: Create Task =====
createResp = zoho.crm.createRecord("Tasks",taskMap);
if(createResp.get("id") != null)
{
info "Task created";
}
else
{
info "Failed to create task";
}
}
else
{
info "No related Memberships found for ID: " + membershipid;
}
}
catch (error)
{
info error;
}