//index.php
<?php
$data = $_GET['artist']; //This makes a GET Variable,which will hold the "artist" value.
switch($data) //Here we are going to check the "artist".
{
case 'eminem': //In case the "artist" is eminem
    echo "Do you think eminem is in...?"; //Do this and that..blah
    break;

case 'bieber': //In case the "artist" is bieber
    echo "Do you think Justin Bieber is in...?";
    break;

default: //If none "artist" is selected
    echo "Please select an artist to vote!";
}
?>