I'm not sure what this means. A CodeRunner question involves constructing a program in some language by combining a student answer with the various test case codes, sending it to the Jobe server, getting the output back, and comparing the output with the expected output.
If you want to use selenium, I would assume you'd be testing some web page somewhere. Is this one the students have implemented? If so, you have a problem because Jobe isn't normally allowed to access external resource - it's a very tightly locked down sandbox server that is stateless and just runs a program in some language. It's not designed to support student webpages.
I suspect CodeRunner is not the right tool for whatever you're trying to do. Could you present us with a CodeRunner question that you'd be asking the students? It would need to specify exactly what code the student is meant to write and include a set of testcases, each containing the testcode you'd use and the expected output from that test.