Frihost certainly should be able to run MyBB, I have done it before with an older version. If there any error message that is being displayed? Also I think it has an install script, can you confirm that you have tried this script and that the database is configured?
I don't understand the trouble you could have with setting up mybb. They practically guide you through it with the installer. You should go to the main MyBB website and ask for support on this. I'm sure many of the members would be happy to help you.
Tesa, If you are still having issues I can write a full how-to for the installation for MyBB. So if you need it then just ask.
i think it will be better if you can provide a screenshot of the error.