Then, awareness of social problems would be promoted at school, so that everyone can be educated and, in caseas a result, provide solutions.

And finally, I would avoid every tiype of discrimination and try to educate children to love diversity, not to be xenophobic.

There are a lot of more things that I would do, but therse are the main ones.

Secondly, there would not existbe any poor or rich countries, since every person alive would get the same opportunity, no matteries regardless of where they are from.

Then, awareness of social problems would be promoted at school, so that everyone canwould be educated, and, in casewhen necessary, provide solutions.

And finally, I would avoid every tiype of discrimination and try to educate children to love diversity, not to be xenophobic.

There are a lot of more things that I would do, but therse are the main ones.

Secondly, there would not exist poor or rich countries would no longer exist, since every person alive would get the same opportunity, no matter where they are from.

Reworded to sound more natural.

ThenFurthermore, awareness of social problems would be promoted at school, so that everyone canould be educated and, in case, provide solutions.

"Could" fits better here, since the previous clause also used the conditional "would."

And finally, I would avoidsupress every tiype of discrimination and try to educate children to love diversity, not to be xenophobic.

"Avoid" doesn't really fit in this sentence, since it's sounds like you want to actively do something against discrimination, not simply avoid it.

There are a lot of more things that I would do, but therse are the main ones.

If I rRuled the wWorld...

This is how it would look in title case, in which the first and last word and any other important words are capitalized.

Secondly, there would not bexist poor or rich countries, since every person alive would get the same opportunity, no matter where they are from.

"Exist" isn't incorrect, but it appears excessively formal/serious in this application. One way to keep the term without it sounding unusual would be to say "Secondly, poor or rich countries would not exist, since..."

ThenNext, awareness of social problems would be promoted at school, so that everyone can be educated and, in case, provide solutions.

"Then" is usually used in reference to a specific sequence or an explanation. For example:

First, I got out the bread. Second, I took out two slices. Then, I put peanut butter on them.

OR it can mean "because of that" or "as a result of that" like here:

First, I would help end all wars. Second, I would give everyone equal opportunity. Then, everyone would have a chance to solve the world's problems.

So I think "next" makes it clearer that you're moving on to your third item.

And fFinally, I would avoidprevent every tiype of discrimination and try to educate children to love diversity, not to be xenophobic.

Including "and" is usually discouraged, unless it serves an important literary purpose--I don't think it is necessary here.

Saying "I would avoid every type of discrimination" makes it sound like you would personally not discriminate, but it doesn't make it sound like you would try to prevent discrimination in the world. Because your other ideas are about how you would change things in the world, my correction seems to keep things flowing a bit more smoothly.

Another way to end the sentence could be:

...to love diversity and not be xenophobic.

There are a lot of more things that I would do, but therse are the main ones.

If you're referring back to what you discussed, "these" is better. You could also say "the one's I mentioned are the most important" or something like that.