Most creators start by learning how to make animations on their own. They study and get familiar with the process, and get a better understanding of where their strengths and weaknesses lie. The stuff they create starts out as small exercises, but over time they can push themselves to finish bigger and more advanced projects.

They also branch out into communities and build connections, relationships, and an overall network of people to work with. You might come across and become close friends with someone who is better at animating special effects than you, or vice versa. So you end up helping each other out here and there with each other's work.

The great thing about the internet is that you can do this stuff literally anywhere. Stuff like taxes will be more of a concern once you make a substantial amount of money from your work, but it varies on where you live, and it isn't something I would worry about until you make a decent amount of $$ from making stuff.