Make sure every line you add into english.lng ends with a semi-colon (

- that's what PHP needs to know as the end of the instruction/command/function.
Leave yse141.ya alone, that was used during the install. You need to edit english.lng (which you did) and add a line. Double check your $txt[] and your $img[] lines again to make sure there isn't a typo.
Then you need to find this:
$img['postEvent'] = '<img src="' . $imagesdir . '/calendarpe.gif" alt="' . $txt['calendar23'] . '" border="0" />';
and add this right after it:
$img['recentq'] = '<img src="' . $imagesdir . '/recentq.gif" alt="' . $txt[889] . '" border="0" />';
You also need to edit index.php in the section where it defines all the action=stuff. If you're using v1.5.0, it will be after
$actionArray = array( . If you're using v1.4.x, it will be in one of the FastFind sections.
In the subs.php, it looks like you did the changes correctly.
HTH, MM