Scan for issues/Run Cleaner

I'm not computer savvy. I would like to use CCleaner very much. I want also to remove any crap from my registry. Will CCleaner clean my registry? Will this not mess up my registry as I do not know even how to re-install Windows. What is the difference in Scanning for issues & fixing those issues and Analyse & Run Cleaner. I have read here on this board that CCleaner does not remove important files, is this right? Thanks for your patience. <_<

Analyze & Run Cleaner is for Appilcations. Scan for Issues amd Fix Selected Issues is for Issues. CCleaner won't mess up your registry at all. It will create a backup incase you have any problems at all.