Connecting third-party library to Qt

Connecting third-party library to Qt

I am trying to get the LIBS and INCLUDEPATH commands working, and I'm not
sure I'm going about this in the right way.
I have a directory, with an arbitrary name of "testinclude", and inside it
contains a .lib called "Connect.lib", and a .dll called
"ConnectLibrary.dll" and another directory called "include" with a bunch
of header files. I need to be able to write code in Qt that uses these
header files, which then in turn use the compiled symbols in the .lib/.dll
files.
So I added this to my .pro:
INCLUDEPATH+="testinclude"
LIBS=Connect.lib
..but I'm just guessing on what the correct layout of information should
be here, especially for LIBS. Is it the name of the .lib or of the .dll?
Is the extension included? I don't really understand what is happening
here. When I try to build, it just says that "error: Connect.lib: No file
or directory"
My understanding is that the .lib is the actual library info needed for
connecting to the dll, is that right? Therefore, it is what Qt needs to
know about? It's all fairly confusing for a newbie.