herculesnetwork on "how to write the output of this function in field 'tags' on post-edit"

how to write the output of this function in field 'tags' on post-edit the dasboard the worpress?

$input = array("neo", "Morpheus", "Trinity", "Cypher", "Tank");
$rand_keys = array_rand($input, 2);
$mixnames = $input[$rand_keys[1]];

Thanks to all.