AWS SQS - Where to put `MessageGroupId` field?

Regarding Amazon Simple Queue Service (aka AWS SQS), is there way to add the field MessageGroupId to pass in the required value for FIFO queues?

I was expecting to see the MessageGroupId field to be under the Message Body field.

If I don’t include the MessageGroupId value, I get the following error message:

“The request must contain the parameter MessageGroupId.”