How do track your HR contacts during interviews

I save it with their name, org name and the position the we've discussed about

How do you get these contacts in first place though? I am looking for a new job as data engineer with 2 years of experience and I am unable to find any hr contacts, cause I just don't know how. One of my seniors recently made a switch, he had a huge network of hr contacts, I asked him how did he get all those. But didn't get a proper answer, just some vague response

Currently I'm using notepad++, also tried huntr something app. You could also try Google sheet or notion