You got an unrelated answer because you didn't fully explain what you wanted.
Try doing this:
I'm not sure if the div id is static or dynamic. If it's static, then use this:
If not, use the class name
x-grid3-hd-last_tweet_time which seems to be the identifying class for that div. If there are multiple elements with that class, then you need to use querySelectorAll and specify the index of the target element.
If this is totally not what you're looking for, then explain a little bit more.