JohnT,
Just as another way of putting Del's help, when you click on the 'Insert Hyperlink' button you get this code entered in to your post (but with square brackets rather than curly ones):
{url}{/url}
Insert your hyperlink before the first close bracket and write something interesting after it but before the next open bracket:
{url=http://connect.garmin.com/activity/124649625} This is my route for that night{/url}
Now with curly brackets replaced with square brackets it looks like this:
This is my route for that nightTo share your Garmin routes you'll need to change the public access permission either in your default settings or for ride-by-ride if you only want to share specific rides; it's the padlock icon just above the summary box that the tip info changes to 'Activity Privacy' when you hover over it.