The story of Solo Leveling is about a weak hunter named Sung Jin - woo. In a world filled with dungeons and monsters, he starts off as an E - rank hunter, which is the lowest rank. But he gets a mysterious system that allows him to level up and become extremely powerful over time. He faces various dangerous dungeons and strong monsters, and gradually rises to become one of the most powerful hunters in the world.
You can start from the chapter where the anime ended. Usually, there are online forums or manga communities that can give you the exact chapter number.
There might be new characters who are the masters of certain types of magic or skills that haven't been shown much in the story yet. For example, a character who can control time in a very different way from what we've seen before. Or perhaps a character who is a master of illusions and uses that to deceive both enemies and allies. There could also be new characters who are related to the antagonists in some way, like a henchman with a special power that makes him a tough opponent.
I'm not sure exactly who the new characters are without reading it fully. But it's likely there will be some new hunters or allies for the protagonist.
In Solo Leveling New Story, the protagonist from the original series is bound to be a central figure. He's the one with the unique leveling ability. However, we can also expect some side characters to have more prominence. There might be a new mentor - like figure who guides the main character in his new adventures, or a new rival who challenges him at every turn. And don't forget about his friends and family, who may also be part of the story and influence his decisions.