How do I see QWT widgets in QT creator?

My system is as follows:
RHEL 6.7
QT 4.8.4
Qt Creator 3.0.1 GCC 4.4.7
QT Designer 4.6.2
QWT 6.1.3

I installed QWT. None of the QWT widgets show up in the designer window. How do I install QWT to have designer display all the widgets in the left display window like it is supposed to work. Creator, Designer, and QT all work fine together.

Thanks in advance for any help.

EMP

How did you install Qwt?