I am new to Qt development and i am use in Qt with visual studio 2008 how i use QWT for visual studio 2008 if some one have experience about that please help me.
Assuming that you have a licensed version of msvc2008 you need to have installed "Qt's vsaddin.":http://qt-project.org/downloads#qt-other The vsaddin does allow loading the qwt.pro file from the source directly. All you have to do is compiling the QWT libs. Afterwards you can use them in your own projects.
IIRC there are separate .pro files for the examples. Those you can load as well and do the compilation of the examples. Having done that part you have a pretty good understanding on how to use with your applications.
In case you have only msvc2008 express version, you cannot use the vsaddin. In this situation it is probably best to install Qt creator as IDE and use it either with msvc2008 compiler (should be detected automatiocally by creator) or with the MinGW compiler.
Is it possible to add the QWT plugin to the Qt Designer in this case?