1. Ensure you have used _e(), __(), _x() etc. functions in your theme. Use unique text domain as argument (for example, __('Poetry', 'myblogtextdomain'))
  2. Install _Poedit_, create new catalog (.po file) and save it in [themename]/languages/ with locale name (ru_RU.po, en_US.po etc.). In catalog properties leave Language field empty, in Sources paths use ../../ as base path and theme name as a Paths field group entry
  3. Use Update command in _Poedit_ to scan theme files for strings to be translated
  4. Translate these strings and save the file. Poedit will automatically create .mo file
  5. Upload them both (still to [themename]/languages)
  6. Insert function that will load text domain in functions.php:

    add_action('after_setup_theme', 'setup_textdomain');
    function setup_textdomain(){
        load_theme_textdomain('myblogtextdomain', get_template_directory() . '/languages');