Practice! Get a camera, or even the camera on your phone, and go to the zoo to observe the animals. Take a ton of photos and then go through them with a critical eye. Which photos are interesting? Why do you think those ones are better than others? Would you be able to recreate this if you had to do it again? Especially if you're feeling stuck, look at work you admire and try to understand why it is good. Repeat this forever – a photographer can never get too much practice.
Once you feel like you have honed your skills, sharing on social media can be a great way to gather feedback from your peers and get exposure for your work. Many modern photography careers have been launched from a well-curated Instagram feed. Seek out hashtags related to the photos you're posting and use them on your posts to get the most eyes on them. At this point, you'll have a great portfolio of work that you can use as you contact potential employers. You may even see opportunities to make money or connect to people working in the industry on Instagram.
Before you can be a wildlife photographer, you have to learn how to be a photographer. I'll assume you own, or have access to, a camera. There is a wealth of information on line and in books that will help you learn how a camera works and how to use a camera to capture the images you see. I'm certain there are books on wildlife photography and photographers that will be helpful. There is no substitute for doing your research on a subject that interests you.
Regarding wildlife photography, once you have become proficient in the use of a camera, you can begin to accumulate wildlife images for a portfolio. Look at the work of well known photographers, your work needs to be as good as theirs. As you develop your portfolio, you can begin to make contact with organizations, magazines, etc. that can use the type of images you are capable of producing. Best of luck.