Try this one…
$w.onReady(function() {
$w('#dataset1').onReady(()=> {
$w("#input1").value = $w("#dataset1").getCurrentItem().fname;
});
$w('#dataset2').onReady(() => {
$w('#dataset2').setFieldValue('fname',$w('#input1').value);
$w('#dataset2').save();
});
});
And also take a look at this one, if you are using Wix-Forms…
…and this one…
And i also ask myself → where is your SUBMIT-BUTTON-CLICK in the code?