Who are UsingUses Marijuana?

She told me that in her school, marijuana can also be found in her school, although it's illegal to be used there.

"She told me in her school" = "she told you" while located in her school

"She told me that in her school" = "she told you" something about things that happen in her school

She noticed a few Ruxxxx students from one country trade marijuana, but they never smoke it, and very few Chinxxxfrom another country touch it either.

I realise some eastern asian languages use 〇〇 replacement as censorship, but we don't really censor like that in English. The closest would be using asterisks mid word like R****n but for something like this it would be more natural to either use uncensored names (especially when it's obvious that these are Russian and Chinese anyway...), or to use generic language.

Chinxxx also has the problem that it's going to be read phonetically the same way as another word that is a slur on Chinese people.

When I asked her how about students from other nations?,

You've two options here, you can quote the entire question: When I asked her "how about students from other nations?" or you can not quote it, but then you need to include the following clause in the same sentence, rather than use a question mark. That's because the question mark ends the sentence, and this sentence is incomplete on its own.

She gave me an interesting answer: "I don't think Nigexxxrian students have money to smoke, nearly all smokers are Canaxxxsnative students."

Who areis Using Marijuana

She told me in her school,that marijuana can also be found in her school, although it's illegal to be used there.

Just a few unnecessary words that make the sentence more difficult to understand.

She noticed a few Ruxxxx students trade marijuana, but they never smoke it, and very few Chinxxx touch it either.

You can't use either here, because the situation of the two students groups are not the same.

When I asked her how about students from other nations?.

This is not a full sentence. You could have said, "When I asked her about students from other nations, she gave me an interesting answer."

She gave me an interesting answer: "I don't think Nigexxx students have money to smoke, n. Nearly all smokers are Canaxxxs students."

Who are Uis using Marijuana

She told me in her school, marijuana can also be found in her school, although it's illegal to be used there.

She noticed a few Ruxxxx students trade marijuana, but they never smoke it, and very few Chinxxx touch it either.

Since Ruxxxxx students trade the marijuana, they touch it, so "either" shouldn't be used.

When I asked her how about students from other nations?,

Sshe gave me an interesting answer: "I don't think Nigexxx students have money to smoke, n. Nearly all smokers are Canaxxxs students."