There's a few ways, but on the last tab you could set the action of the submit button, to trigger a JavaScript query object containing code to pull the values from each of the form controls and then run the appropriate data query you want to run with the results. In your data query you would set a placeholder object to use as a parameter as described here:

https://docs.lowcoder.cloud/lowcoder-documentation/business-logic-in-apps/write-javascript/javascript-query

Your query could look something along the lines of:

let payload = {name: form1.value.name,email: form2.value.email}targetQuery.run({payload: payload});

Yes, that it pretty much it. You would need to collect all the form data, which is accessible via JavaScript. Then you can merge it into the format your backend need - and then send it.