I am totally new to all of this, and I need safe and reliable crypto tumbler. So if you can share one here, please do.

There's no such things as a beginner-friendly bitcoin mixer. Well I mean there's no such thing as non-beginner-friendly bitcoin mixer. It is easy to use it, there's no convolution. And yep, I can share the one you will like, check this bitcoin tumbler https://tumbler.io . Just follow simple instructions there and you will be okay.