You can't:
Sending newsletters is allowed as long as you stay within our email limits, whether you're using Hostinger Email or Titan Email. However, no mass mailers/spammers are allowed according to our Terms of Service.
If you break the T&C's, it will be spotted very quickly, and your email service shut down.
Quote:
I am confused, about which tools/technics/programming language can be used for this task. I'm a beginner...
Even if you could (without being shut down ASAP) the best language is sim0ple: the one you know that works in your environment.
All of the web enabled backend languages support email sending, but how they do it depends on the language / framework involved.