You can't (on this specific page). Linking to a particular subsection (such that a user's browser automatically scrolls to it) requires the use of HTML Anchors for each section, which that page does not have. More specifically, the heading would need to either contain or have nearby:
- An
A (anchor) tag
- With an
id or name property
If those criteria are met, then you can link to
http://example.com/webpage.html#anchorName
where anchorName is the value of the name or id property.
That Trello page just has a header though:
<h2>Card Aging</h2>
So it can't be linked to. If they had used instead:
<h2><a name="aging">Card Aging</a></h2>
then you could link to it like such:
http://blog.trello.com/introducing-power-ups-calendar-card-aging-and-more/#aging