Thank you for all answers.
@vfclists
is there an easy online way to do it?
At the moment I make a full copy of my project after every step which works.
And at the end of the day I use the freeware PersonalBackup, which was originally written by a Delphi genius who wanted to safe his own project files in a way, they make sense. e.g. nobody wants to save the backup-folders or huge exe every day. This is the Swiss knife for making an offline copy.
Git is the tool you probably want to familiarize yourself with, but the UIs available for it are horrendous.
Grasping the concepts behind it through the tools available is rather hard, and far as Git is concerned, installing Emacs just to be able to use Magit is probably worth it, whether on Windows or Linux.
TortoiseGit on Windows will be good to get you going.
If just tagging and saving snapshots is your main need it then any backup tool that does tagged and labelled snapshots of a directory will be fine, like the PersonalBackup tool you mentioned.