You've just installed the source, now you have to compile it and then install it, there are many tutorials on the net how to do that. But you should skip that part, and download the expect compiled rpm and install it directly. You can even install via Internet, as in : "rpm -Uvh http://server.com/expect.rpm" - just replace the path.
Also, what is your OS ? If it's RPM based package system, use their repos and download via yum, yast or the respective instrument.