I seek a friend!

I seek a friend!

Hi! Your sentence is grammatically correct! A more common option: "I'm looking for a friend."

Hi, I want to find people with whom to communicate and learn to speak in English!

And I can help learn Russian)))

Your version is grammatically correct, but adding 'can' is a great improvement :-)

Hi, I want to find people who I can communicate with and could help me learn to speak in English!

"to" connects "want" with "find." It is telling your reader you "want to find people."

"with" was added after "communicate" to show who will you will do this with.

I added "could help me," because you are putting two thoughts into 1 sentence. imagine it like this

"Hi, I want to find people who I can communicate with in English."
+
"Hi, I want to fin people who could help me learn to speak in English."

I can also help you learn Russian)))

"Can" was put there because it is used to show that it is something you offer.

I can help you = Я могу помочь тебе/вам.

can = могу

"You" was added, because you want the reader to know you are talking directly to him or her.

"And" was removed, because in this situation, you cannot begin your sentence with it. And, in this case, meant "also" or тоже. So, it was changed to "also," then moved after "can," because you are telling your reader that you want help from them, but you will also help them too.