Updating fedora with yum
Regardless, I'd still recommend upgrading Fedora to reduce dependency complications.
According to the Upgrading topic in the wiki, there was a method where you could put a DVD in your system for the next version of Fedora, and Anaconda would attempt to upgrade your system.
Make sure that your firewall allows configuring RHSM, for more information see How do I access RHSM (yum) through a firewall? General information on RHSM can be found in Red Hat Network Subscription Management, while FAQ for Changes to Red Hat's Entitlement Platform with RHEL 6.1 and 5.7 provides a quick overview and a comparison with RHN.
Before installing an update, make sure all previously released errata relevant to the system have been applied.
Customers using older versions of Red Hat Enterprise Linux must continue using RHN Classic. System can also be registered via the command line by using the "subscription-manager" command.
Refer to FAQ for Changes to Red Hat's Entitlement Platform with RHEL 6.1 and 5.7 and What's the difference between management services provided by Red Hat Network (RHN) Classic and Red Hat Subscription Management (RHSM)? To register your system either trough the GUI or form the command line follow the instructions in the Using and Configuring Red Hat Subscription Manager guide.