How to add options to the plugin page?

I can’t find a more or less clear example on how to create additional fields, so may be someone can help me here? Here is my code:

function __construct(){
    add_action('admin_init', array($this, 'plugin_admin_init'));
}

public function create_fields(){
    register_setting('dleToWp_options', 'database_name');
    register_setting('dleToWp_options', 'database_prefix');
    register_setting('dleToWp_options', 'version');
    //Stuck here
    // add_settings_section('dleToWp_options', __('Settings', 'dleToWp'), NULL, 'dleToWp');
    // add_settings_field('plugin_text_string', 'Plugin Text Input', 'plugin_setting_string', 'plugin', 'dleToWp');
}

public function settings_page(){

    echo '<div class="wrap">
        <div class="icon32" id="icon-tools"></div>
        <h2>'.__('Database converter', 'dleToWp').'</h2>
        <form action="options.php" method="post">';
    settings_fields('dleToWp_options');
    do_settings_sections('dleToWp');
    echo '</form></div>';
}

I nee create 3 fields: Database name, database prefix and select box of versions.