<div class="proplist"><span><?php _e('Price','my-text-domain'); ?></span> <span class="propval"> <?php $price=get_post_meta($post->ID, 'wtf_price', true); echo $price; ?></span></div>That's correct.
And one more question: 'my-text-domain' should be just main website address, or exact page?
It's whatever you want, but generally we use the same name as the theme or the plugin directory
Should I just add something like:
/*
* Text Domain: whatever
*/
That's not the important part. the most important part is to declare the text domain with the function load_theme_textdomain as described in the this part of the codex.
And finally you will have to create your po/mo files to translate the string (the plugin Codestyling localization is great help for doing this).
And nobody is going to explain.
That's free help on a forum. You need to be patient. Sometimes you don't even get help because there's so much questions that volunteers just cannot answer to everybody.