"unexpected parameter"

[Dolphin1543]

Every time I try to open a rom with Dolphin it gives me something called "Dolphin message" and says this:

"Usage: Dolphin [/h] [/d] [/l] [/e <str>]" etc ...

and gives me a list of commands and what they do like:

"/h -- help Shows this help message
/d -- debugger Opens the debugger" etc ...

and at the very bottom says

"Unexpected parameter 'C:\Users\Welcome\Desktop\smb2.gcm"

I have no idea what this means. Can anyone please help me?