Inserting a teaser break tells the system where you want to break your page up so that a smaller portion of it shows up at the front page of your website or perhaps the stream, whether it be a blog, news bulletins or even product descriptions.
The system makes some assumptions about where you may want to place a break. Sometimes you may have a very specific idea about where you would like to see a break. This is where the insert break button helps.

Sometimes the break comes at a place you really don't like. For example, here we see the break automatically inserted where we don't see any of the content besides the Facebook "fan us" paragraph. Typically, the system will break for the teaser right at the end of the first paragraph.

Once you are on the page, you will see the edit button/tab. Click it to edit the page.

Hover your mouse over the button that looks like a page with a dotted line in the middle. That's the insert break icon. It will tell you so if you hover over it.
Make sure your cursor is where you want the break before you click the insert break icon.

You should see a <--break--> indicated right about the location it will break up the page. In this case, we wanted all the text to show on the front page of our website.

Once you save or publish the edited page, the break will change where the "read more" begins.
