This is a good start! I think I understand what you are saying, but I'm not completely certain about the first sentence. When you say, "introduce," do you mean that you want to learn about these yourself? Or do you mean that you want to teach others about them? When you say, "oppositions to teaching," do you mean the challenges a teacher faces? Or do you mean the requirements for teaching? Your second sentence would be better worded like this: "I have loved working as a teacher my whole life." Your last sentence... es perfecto!