I want to start a website (or few) but I am a bit new at this

Hello everyone.

So, I want to start few websites. Of course, my main idea is to eventually make some money with it, but I do understand that it needs work before that and I am willing to that.

I want to start with the simpler site since I am a little new at this, and then get to affiliate websites and etc. This first more simple site, which I would also use for teaching myself everything, would be some type of a blog/content website, like general knowledge or news, or specific topic and niche.
But, the main thing is – I am new at this so I have a tooon of questions really. I don’t even know where to start with them.
So my first questions would be:

– Would it be alright if I start with website builders and free themes to create the website? (I can’t hire a web designer right now)

– How to make my website secure for visitors, and just generally secure? (I know that many website builders already have some security features and possibilities but I want to know if there is anything else I could do along with that)

– Any other useful advice for a beginner? Where and how can I learn more?

(I apologize if I posted this in a wrong section – I’m new here)

Thank you all :)