I'm very happy to see you're curious, and would love to answer your questions. Thank you for being open minded! :)
To get there, Communists think that the working class should take power, political power (that's what they call dictatorship of the proletariat) and control of the means of production. Nowadays, those are both controlled by the capitalist ruling class (directly and indirectly). If the working class controlled the means of production, that means they can operate it for their own needs instead of for profit.
You're probably thinking "well that doesn't explain how it actually happens". You're right. The exact mechanism for the working class reaching power is something I've admittedly studied a lot less, and given their Communists are yet to succeed with that, I imagine the theories there aren't complete.
The essential idea, though, is that the working class needs to become class conscious. In other words, aware of... Basically what we've been talking about. How capitalism is and how the different classes operate within the realm of capitalism. Then, the working class must organize together as a United force, and seek to overthrow the capitalist class.
In an ideal world, this would be pretty easy. Workers are the core of the economy, so workers could simply stop working or just operate their factories as they want.
In reality, things aren't as smooth. There will always be unconvinced workers. There will be police that, if you take over your workplace, they'll violently put you back in your place. This is something we've seen before in history. This is where things could get violent and bloody. The working class must be prepared to fight back.
Please let me know if this answers your question.
That's a different kind of plumbing than what I was talking about, and I only simplified it for the case of an example. There's nothing preventing people to organize into a complex team of plumbing specialists, just like they would learn advanced engineering or medicine, and build chemical plants and factories or hospitals. Again, it would still be driven by need. If your need drives you to be an individual plumber for suburban homes, it can also drive you to be part of a specialist plumbing team in a large city.