jesus christ!!! he's just a newwwwwbieeeeee.
anyways maaan, KDE is a desktop environment. others include Gnome, XFCE, etc.
if you are a newb. you're probably better off using KDE, so just like if you were using windows, follow the simple yet subtle instructions this senior member dude has given you, for he is wise and probably uses i686 optimized packages, not like me, for I have a crappy computer and live on i486 crappy systems.
i am not kidding, linux is fun in the sun baby.