OK, now its time to do some reading so that you do understand what is going on. One of the more common gotchas in Linux comes from using these automated tools to update and upgrade systems when you don't understand what is happening. One of the biggest issues is automated dependency resolution, where you install one package that requires other packages in order to function. Tools like Yum will automatically install those dependencies, and depending on what those packages involve, can bork your system. It has gotten a lot better but you still need to understand what is going on when you allow automatic dependency resolution.