Interpreter question (basic)

I am trying to learn Python for fun.  I bought a Great Courses program.  It suggests PyCharm.  Here's my problem.  I am using a MacBook Air with OS 10.13.4.  I downloaded Python 3.6.5 and the community version of PyCharm.  I'm having trouble matching the teaching lessons to the software.  I think it is because the interpreter is for Python 2.7.  Does this make any sense?  If so, how do I fix it?

Example:  the input won't accept a string value -  I keep getting error messages.  When I use raw_input it works, but isn't that a Python2 2 command?  

Thanks for any help.