[Ubuntu 9.04] MySql datadir?

[lainmaster]

I tried adding it to the my file specified in the linux page, and also changing some other values, but it didn't change anything. I read that for linux, the datadir didn't work in XAMPP, but I don't understand how to change it. I'm kind of an Ubuntu newbie. What can I do to set the mysql datadir? Also, the datadir must point to a drive in NTFS. (The drive mounts fine and I can access it fine with other programs, but just in case).