New user seeks simple help

Hi
As above, I am trying to create a set of rules that monitors a folder and looks for the latest added file. Once found I would like it to copy that last file to Dropbox. At the same time I would like the rule set to monitor the Dropbox folder so that the file being added to Dropbox would replace and therefore delete the file held on Dropbox. This would save me a whole load of Dropbox storage as I hope to be able to apply the same rule to lots of single files in folders I want to backup to Dropbox.
I hope that is clear and please forgive a new users ignorance!
Cheers...
As above, I am trying to create a set of rules that monitors a folder and looks for the latest added file. Once found I would like it to copy that last file to Dropbox. At the same time I would like the rule set to monitor the Dropbox folder so that the file being added to Dropbox would replace and therefore delete the file held on Dropbox. This would save me a whole load of Dropbox storage as I hope to be able to apply the same rule to lots of single files in folders I want to backup to Dropbox.
I hope that is clear and please forgive a new users ignorance!
Cheers...