Using the Media uploader in wordpress make sure to include wp_enqueue_media();

wp-using-media-uploader.php

			(function($){
				var frame;
				$(function(){

					$('#cloner-csv-button').click(function () {
//						var $el =$(this);

						if(frame) {
							frame.open();
							return;
						}

						frame = wp.media.frames.nsClonerCSV = wp.media({
							title: 'Choose Search and Replace CSV',
							library: {
								type: 'text/csv'
							},
							button: {
								text: 'Select CSV'
							}
						});

						frame.open();
					});
				});
			})(jQuery);