Hi GNeitz,
It usually helps to know a bit more about what you are trying to do. Are
you talking about during a show or during edit? What version of PowerPoint
are you using?
If you are using PowerPoint 2003 and trying to hide the textbox during the
show (to be displayed with an animation), just select the text box. Then
right click and select Custom Animation from the menu list. In the Custom
Animation Pane, select Add Effect => Entrance => Select a type (like Fade).
Now the text box will fade in when you click the advance during the show.
There are a billion adjustments you can make to the animation, but that is
the basic default method.
Bill Dilworth