upgrade fedora from 14 to 15

1. chang to root user

　　command:　　su -

2. clean the repository

　　command:　　yum clean all

3. update your repository to the latest.

　　command:　　yum update

4. install the preupgrade

　　command:　　yum install preupgrade

5. run the preupgrade and check the checkbox and then select fedora15 and wait for the process to successfully end.

　　command:　　preupgrade

6. remove the unsupported packages

　　command:　　package-cleanup --orphans

7. reboot to test the latest version of fedora.

Sun Mar 27,20:17 at  home by Haria