This tutorial shows step-by-step screenshots for using up2date - The Red Hat Update Agent.
If you see red alert from bottom right screen, it tells you have new updates.
In order for up2date to work properly, make sure you have following in /etc/sysconfig/rhn/sources:
yum fedora-core-1 http://download.fedora.redhat.com/pub/fedora/linux/core/1/i386/os yum updates-released http://download.fedora.redhat.com/pub/fedora/linux/core/updates/1/i386 Or see HOWTO: How to fix rhn-applet for more information.