[newbie] DOS based directories

[vern]

Hello All,
      I'm presently experimenting with  Wine (windows emulator)
not the drink!  I have a question as to how Linux recognizes
two word directory names?  ie: /Program Files/   How do you
represent the space between words?  I have tried the following:
"Program Files"
"Program_Files"
"Program%20Files"
The last one came from watching how X represents them.
I have tried all the above from the command line and nogo.
This may be an easily found answer but I keep overlooking it!
Thanks!
Vern