What's the difference between は, を, へ

My neighbor is not from Japan. But she can speak English.She has a kid who is first-grade elementary school stundent.She wanna teach Japanese to her kid. Cause I can use English a little, I help her.
May this note reach those who share the same feelings as her.
I apologize for my poor English and any grammar mistakes I may make.　Please forgive me. If you don't mind, I would appreciate it if you could correct my grammar.

"は" like "be" meaning equal.

An elephant "is" big.
ぞう "は" おおきい。

わたし"は" せいと です。
I "am" a student.

But, in Japanese, "は" is used before verb.

The river flow.
かわ "は" ながれる。 

"を" is used as object pointer.
When we write sentence in English, we make form SVO,
but, in Japanese, we write "S は O を V"。

I wash my face.
わたしは かお"を" あらう。

"へ" is used like direction.
We use like "to" or "for".

I go to Tokyo.
わたしは とうきょう"へ" いく。