By default, the TwentyTen theme shows the titles of the last 5 posts on the sidebar.
This number is easy to change. Here’s how to do it:
1. Log into WordPress using an administrator account.
2. Select “Widgets” on the appearance section of the sidebar.
3. Click on the arrow to the right of the “Recent Posts” widget.
4. Now change the number of posts to reflect how many you would like to appear on the sidebar.
5. Click on “Save”.
There are, of course, plug-ins that allow more flexibility than this simple widget. I shall be looking into those another day.