I found this web page https://www.arduino.cc/en/Tutorial/EEPROMWrite about EEPROM but don't quite understand how to use it to store a value.
What part of that example in the Tutorial did you not understand?
There are additional examples to be found in the IDE under File>Examples>EEPROM.
If you are using one of the more recent versions of the IDE, the built in EEPROM library contains functions to write and read multi-byte variables.