The Heartbleed fault has been patched for Ubuntu, so if you have had software updates in the past week or so, you are probably patched already.
To check the build date which will show the patch (not when your version was released) , open a terminal and type
openssl version -b
It should show a build date of Mon Apr 7, a UTC time, and the year 2014.
If it doesn’t, then type
sudo apt-get update
When it finishes, type
sudo apt-get upgrade openssl
That should take care of it for you.