First part:
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I've installed qwt-6.0.1 in C:\qwt-6.0.1\ by following steps:
qmake qwt.pro
mingw32-make
mingw32-make install

Then I tried this for running examples:
cd examples
qmake examples.pro
mingw32-make

So with this I'm successfully able open examples in Qt creator, build & run given in the C:\qwt-6.0.1\examples directory.

Second Part:
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I've created a project in D:\My_App\ directory. I want to use qwt library to draw required graphs. In examples I find some files with .pri extension, but I don't have any in my project folder. Then I edited my My_App.pro file to configure the paths:

# Project created by QtCreator 2012-04-18T09:43:46
#
#-------------------------------------------------

QT += core gui

INCLUDEPATH += C:\qwt-6.0.1\include

LIBS += -L"C:\qwt-6.0.1\lib" \
-lqwtd \
-lqwt

TARGET = My_Application
TEMPLATE = app


SOURCES += main.cpp\
mainwindow.cpp \
paramdisplaywindow.cpp \
paramwidget.cpp \
devicestate.cpp \
loginscreen.cpp \
graphdialog.cpp

HEADERS += mainwindow.h \
paramdisplaywindow.h \
paramwidget.h \
devicestate.h \
loginscreen.h \
graphdialog.h
#-------------------------------------------------------------------------

If I build the project in Qt creator, the following warning message is appearing:
"warning: auto-importing has been activated without --enable-auto-import specified on the command line."
Then if I run the project, the following message: "The program has unexpectedly finished."

Is that all I need to add in .pro file. Where am I doing the mistake ? Please help me with this. Thank you.