All you have to do is:
- Hook up the power lines to your grid (this step may be omitted if you place the plant close enough to it)
- Hook up the rails to a water loading setup and a fuel cell production & reprocessing unit
- Add the water and fuel cell stations to the trains' schedules
You can find the blueprint at https://factorioprints.com/view/-LlHULCG4GBLePCMm0xZ