In the meantime, you can email us at help@cloudrun.co, let us know your region of interest and time window, and we will happily create the input files for you.
We considered not launching the Beta before the input file creation was done, but we wanted to get feedback as early as possible. I really appreciate your interest and feedback!
If by any chance you decide to go creating these files yourself, the process is tedious but well documented here: http://www2.mmm.ucar.edu/wrf/users/docs/user_guide_V3/users_...
We do plan to start writing short tutorials on setting up simulations and geared toward non-experts.