If your password is abc, just put it in the MD5 hash generator, and the output, which is always a 32-character string, is the hashed password. For example, the OpenSprinkler default password is opendoor, so in the command you simply use:
pw=a6d82bced638de3def1e9bbb4983225c
where a6d82bced638de3def1e9bbb4983225c is the MD5 hash of opendoor.