This is just part of my code. Can someone help?

I need it to post into the database but its not working. everything else is working fine escept for that.

"<select style='width:58%' id= 'selections' name='selections[]' class='selections' multiple='multiple'></select> <input id='clearselections' type='button' value='Clear All Selections' onclick= 'clearvalues()'>

						<?php
						$mysqli = new mysqli('localhost', 'USERNAME', 'PASSWORD', 'DATA_BASE');
						$stmt = $mysqli->prepare( 'INSERT INTO Entries (wp_usermeta) VALUES ('wp_usermeta'.'meta_key');
						$stmt->bind_param( 's', $POST['selections']);
						$stmt->execute();
						$mysqli->close();
						?>
						
						<script type='text/javascript'>
						function clearvalues() {
							$('select#selections option').remove();
						}
						</script>
						
						<script src='/public_html/wp-content/plugins/pmpro-customizations/bower_components/jquery/dist/jquery.min.js'></script>
						<script src='/public_html/wp-content/plugins/pmpro-customizations/bower_components/select2/dist/js/select2.min.js'></script>
						
						<script type='text/javascript'>
							$(document).ready(function() {
								$('#selections').select2();}
						</script>"