Edit Date and "filed under:" lines in Twenty-Twelve Theme

I’m new at wordpress and I have it installed and running, but I can’t find where to edit a few things in the Twenty-Twelve theme.

The blog page for my post shows :

<h2> [DATE] </h2>
<h3> [post title]</h3>
Filed under: [categoryname] — [authorname] @ 12:11 PM Edit This

(Note: This is not all of the actual source, I just included the appropriate header tags to help find this section of the code)

How can I edit this template as follows:
– delete the h2 DATE
– change the [post title] to h2
delete most of the “Filed under:” line and just keep the date

thanks