To add those parameters you have to:

• click the 3 dots on the right side
• then click on parameters
• and in the new popup add a valid json file with the proper parameters

In my example I have this query

SELECT order_number, order_date, sales
FROM cleaned_sales_data 
WHERE TRUE
    {% if from_dttm is not none %}
      AND order_date > '{{ from_dttm }}'
    {% endif %}
    {% if to_dttm is not none %}
      AND order_date < '{{ to_dttm }}'
    {% endif %}

and I added the following parameters:

{
"from_dttm": "2003-05-01",
"to_dttm": "2003-06-01"
}

and then you get the proper results based on the given parameters