Since I'm pretty much the laziest person this side of the universe, I'll tell you the approximate steps, and then you request detail wherever you're stuck, ok?
1) you need to create a site on DW, through Site -> Manage Sites -> New (if you haven't already)
2) local directory must point of course to where you have the files on your HD
3) remote site must be configured with the particular details of your ftp account
4) ok, when you're over, it'll index the site. If you're on developer view (don't ask, I've no idea how to change modes), you've got a list on the right with 'design', 'aplication', 'code',... go to the files menu. There you'll see the whole list of files and directories. Select the uppermost folder (which will be your root web folder) and look for a blue arrow pointing upwards in the icons immediately over that. Press it. Wait. Eventually it'll finish and you'll be back. If there's any error, it'll pop up and stay there.
Ok, it's detailed but most likely not fully appropiate. Just write wherever you're lost, and someone'll try to help