How to include own css on wordpress tinymce editor?

Question

I have added some text on tinymce editor on load.
(Every time you click on Add new the tinymce editor load with this text.)

but problem is how to enable css class which are using in default text.

Thanks

Answer 1

Use add_editor_style

e.g.: functions.php

add_editor_style('custom-editor-style.css');

http://codex.wordpress.org/Function_Reference/add_editor_style

Answer 2

add_editor_style is recommended for theme. You can mce_css filter in plugin. The following sample code is from here

function plugin_mce_css( $mce_css ) {
  if ( !empty( $mce_css ) )
    $mce_css .= ',';
    $mce_css .= plugins_url( 'editor.css', __FILE__ );
    return $mce_css;
  }
add_filter( 'mce_css', 'plugin_mce_css' );