You are going to have to do better than that. We need a lot more information. Please give a compelte detail of your experience as well as compelte system specs.
Simple mistake made here. You are running out of hard disk space. You would solve that by adding a new hard disk drive. You have added RAM, which is something entirely different. RAM is temporary memory which aids in the performance of your PC. Upgrading to more RAM is not a waste of time, but you will not get any free disk space unless you buy a bigger (or extra) hard drive. That is where your 'free space' is held.