Events are always posted on the calendar, but you can get an immediate email when an event you're interested in is posted.  You can remove yourself from these emails just as easily.  Also, if you are interested in being notified about volunteer events, this is how you do that to.

Step 1: Make sure you are logged in, then click your name in the upper right.

Step 2: Then click on Edit profile.

Step 3: Check the boxes that apply (or uncheck them as you wish).

If you haven't yet read and agreed to the liability waiver, you'll have to do that.  Click on the text to open the waiver so you can read it.  Then check the box.

Don't forget to save the changes to your profile.