ok, in the project folder of your Qt project you should have a *.pro file. Open this file and add the include path and lib specifications as suggested in my previous mail.

Next you have to run qmake again to update your makefiles. If you miss that step, you will get the error message again. After that, rebuild your project.

Please note: You should build the libssh2 library before adding it to your project. Follow the build instructions given for libssh2.