dynamically create fields for plugin

I'm trying to create one Plugin. I'm very new for this. For that I want to create N number of fields. So If I click Add button, text field should create dynamically with random id (without duplicate).

See my coding,

<?php
add_action('admin_menu', 'add_karsho');
function add_karsho()
{
    add_options_page('Add Text', 'Add Text', 'manage_options', 'functions','karsho');
}

function karsho()
{
?>
    <div class="wrap">
        <h2>Add Text</h2>
        <input type="button" value="Add" >
        <form method="post" action="options.php">
            <?php wp_nonce_field('update-options') ?>
            <p><strong>Text 1:</strong><br />
                <input type="text" name="text-1" size="45" value="<?php echo get_option('text-1'); ?>" />
            </p>
            <p><input type="submit" name="Submit" value="Store Options" /></p>
            <input type="hidden" name="action" value="update" />
            <input type="hidden" name="page_options" value="text-1" />
        </form>
    </div>
<?php
}
?>

This coding working very fine for that field 'text-1'. If I click, 'Add' button, number field should increase one by one.

Help me...