Did you follow the install directions in the sticky here (also linked under every interface download)?
http://www.eq2interface.com/forums/showthread.php?t=293
If yes please explain better on what step your having trouble with.
You put the ini file into the Everquest II folder. If you cant find your EQ2 folder *right* click on your EQ2 Icon you use to load the game and then left click properties and it should show you the path where EQ2 is installed on your computer.