How to add and remove files from an encrypted folder?

Hi all,

Some time ago I created an encrypted folder (dmg) on my desktop and I filled it with files. I recently wanted to chuck another file in there but I've not been able to do it. From the notes I've seen on the net I understand it should be a case of simply dragging and dropping my files into the folder but it doesn't work for me. I've aslo not been able to delete any files from the encrypted folder... Can anyone please help?? It's been driving me mad! Thanks

 

OK, this is quite embarrassing.. I'm not great at this stuff so I followed an instruction I found online. From what I remember it was pretty much like the one below:

http://www.mactricksandtips.com/2008/04/password-protecting-folder-solution.html

Any ideas what might be wrong?