The official method is to install the fedora package called "preupgrade". The gui will walk you thru the upgrade process.
When I upgraded from 8 to 9, I used an alternative command-line approach, which should work for you as well:
- completely upgrade f9;
- install the fedora-release and fedora-release-notes packages from the F10 repository. You may need to force it with rpm.
- run yum upgrade
As always, BACK EVERYTHING UP first. The upgrade process is not reversible, and if you don't like the results you will need to do a clean install.