First install the new Fedora 16 gpg key.
rpm --import https://fedoraproject.org/static/A82BA4B7.txtthen upgrade all packages using this commands.
yum update yum
yum clean all
yum --releasever=16 --disableplugin=presto distro-sync
you must have a root permission to do all the command above. so use sudo or log in as a root