Once you've downloaded the app, you should see a Dropbox icon appear in your menu bar near your clock. You can check the sync status by clicking on this icon or by navigating to the Dropbox folder from your Finder window and checking the sync icons next to your files.
If you check your account online, are you able to see any files that you added to the Dropbox folder there?
I have the icon on my menu bar now but I don't see away of determing if a file is offline or on my hard disk through it.
Although at set up I specified I wanted all new downloads to go online and not on my hard disks, it appears to me that downloads are still going to my HD (which they are, since that folder is filling) I can't determing where the online folder or or find anyway of making sure that future files go online and do not take up HD space.
I have my hearts set on buying this product but this trial isn't working out so far.
If you open up the Dropbox folder from your Finder window (you should see a shortcut in the left panel), you should see a grey cloud icon next to your files if they're online only. When a file is smart synced as "online only", you'll be able to see the files in your Dropbox folder on your computer, but they won't take space on your hard drive.
You can double check that by using Command+click on the Dropbox folder, or a folder/file within the Dropbox folder, and choosing "Get info". From there, it will tell you the space the file is taking on your hard drive.
If you prefer not to see certain folders on your desktop at all and want to have them only accessible online, then you can use selective sync instead.