Il keep it short. Get the LogMeIn app on your iPhone. It's free. It will guide you to get the application also on your PC. Do it. (The service is secure and safe) Set it up as instructed by the app.
What us it good for? Scenario 1: you're away and need to get something done on your PC. Now you can connect an control your PC as if you're sitting in front of it, literally.
Scenario 2: you need to get an important file on your iPhone. Now you can connect to your PC and copy the file you need to the Dropbox folder or mail it to your phone.