Clicking on Fix selected issues... will remove everything selected. Once you click on Fix selected issues... you will be asked "Do you want to backup changes to the registry?" It's up to you, if you want to or not, but I never had any problems with not backing up. But, I backup my full registry every now and then anyways.

Now a window will pop up saying how many there are and what it is. In the top left, it will say what the problem is, and at the top is will describe the problem in full. At the bottom you have 5 buttons. << >> will scroll through all of the problems. Fix Issue will fix each issue one by one. Fix All Selected Issues will fix all of the issues you have selected. I tend to click on Fix All Selected Issues, because there are so many... Once you are done, just click on Close. Many of them might recreate themselves once you restart your computer, but it's ok. It's a Windows thing.... Lastly, Close will close the Issue Fix window.