Actually it depends on how you learn stuff. I never really used a c++ tutorial, I just have done a lot of programming, learned the basics a few years ago and used google for the rest. I recommend you read chapters 1-8 and create some small projects (fibonacci, hello world; standard stuff really, try to use what you learned). Then go to https://github.com/LUNIServer/UniverseServer/ and download the server source. Try to work out how it works and go back to tutorial when you don’t get something.

While you do that you should start seeing what isn’t done yet or done in a weird way, then try to work on it.

This may take a short or very long time depending on your experience, but this is the path you need to take.

You may need to look into SQL as well and into GIT once you have improved code you want to commit.