Supermon is very friendly. At the command prompt (.) you enter the command letter and then any parameters.
For example, to fill memory with fixed contents:
.F 1800 18FF 00
To transfer a block of memory to a new location:
.T 0800 0BFF 8000
And to hunt for a memory pattern:
.H 0800 1800 20 D2 FF
Sorry I didn't specify this, I guess I've just been using the same format for so long I assumed everyone knew it.

It's the "de facto" standard for Commodore monitors.