How we can make the Earth a better place?

Humans think they are the most important species in the world. It's true that we aren't satisfied following the path set forth by the evolution, but that doesn't mean we can destroy other species in the process.

I think the Earth could be a better place if humans used the technology to take only the necessary natural resources and to protect the environment.

The first step should be to educate everyone about good manners and raise awareness about the importance of taking care of the Earth.  Often it’s (better: It's often) more expensive to try to fix something than it is to destroy it, so it is better leave it alone.
But before that, we must stop fighting and to help each other. This is the most important problem of the humanity.

The next step should be to live in harmony with all other living beings. We could concentrate the population in a big cities and connect ourselves through a good transportation and communication system. That way we would respect the natural evolution of ecosystems.

I think we should focus on making the earth a better place instead of trying to live on Mars already.

This is excellent. You're demonstrating a great ability to compose logical thoughts in English, which often seems like it is the wrong way around for Spanish natives, and I can see that you're trying very hard to use correct pronouns, prepositions, and punctuation. I'm really impressed. Well done, Julia. 

How we can we make do the Earth a better place?

Humans think they are the most important species around in the world. It's true that we aren't satisfied following the path marked out by the evolution but not for that we can that isn't a reason to destroy others paths.
I think the Earth can be a better place if humans use the technology to take only the necessary natural resources and to protect the environment.

The first step should be to educate people in good manners and to be aware about of the importance to of taking care of the Earth. [sorry about the of, of, of, but this is the way speak :( ] Often it’s more expensive to try to fix something than to destroy it so it is better let it be.
But before that we must leave to stop fighting and to help each other. This is the most important problem of the for humanity…

The next step should be to live in harmony with all other living beings. We could concentrate the population in a big cities and connect them through with a good transporter and communication systems. So we would respect the natural evolution of ecosystems.

I think we should concentrate in to do on making the Earth a better place instead of trying to live on Mars already.