So, I started today. Took Pikachu as my starter - edited one of the rules, in that I can keep one Pokemon from a wiped team rather than always keep the starter.

Caught Hoothoot on Route 1, Ratatta on Route 22, Pidgey in Route 2, and a Caterpie in Viridian Forest.

 

Pikachu and Hoothoot fainted to Jackson in the Trainer's School because I'm an idiot; Pikachu and Hoothoot were released leaving me with the Rattata, who didn't faint. I now have to try get through Brock with a Rattata, a Pidgey and a Caterpie. Well, I learnt my lesson about giving up on the grind though. Currently in Viridian Forest and will record / reupdate when I am ready to face Brock. No more pokemon can be caught as of right now.

 

I did make a video, linked

 

It's bad, my headset is kinda gross right now, and this is the first one I've ever made but hey ho, here to learn my friends.

Can someone please explain me the nuzzlock concept?

It's just a way to challenge yourself while playing Pokemon. It enforces a set of rules that just makes everything a wee bit harder, adding to the excitement / achievement if you are into that kind of thing. Bulbapedia has an article on it. https://bulbapedia.bulbagarden.net/wiki/Nuzlocke_Challenge

So much loss already -.- but you can do it!! good luck against Brock!