To clarify, the Heartbleed vulnerability only affects web servers and services and does not affect clients (your personal computer, not being used as a server).
If you are hosting your own website or web services, you can connect to your server and then use the command in the 3rd-party article you linked. This will check to see if your server is running an old version of OpenSSL. I show the full command needed is listed in that article.
It should also be noted that, according to Apple, iOS and OSX web servers and other Apple web-based services were never affected by the Heartbleed vulnerability. Apple software never used the vulnerable version of OpenSSL that was affected.