I dont know what kind of hosting your with(since you said you were uploading) but dnn requires a few special permissions to work. Such as db_owner in SQL-server on the 'dotnetnuke' database. Depending on the Operating System of the server, the users ASP_WP (XP, 2000) or NT_Authority(2003) needs db_owner.
The connection string will most likely not be 'local host' as the server, your web hoster should provide you with details for its connection string requirements.
customerErrors mode="Off" - just makes sure that helpful errors are shown.