私にあった教材があれば、チャットボックスで教えて下さいって英語でなんて言うの？

When you want to ask your teacher to recommend material for you and type their recommendations on the chat box; you may ask in the following ways:
-Could you type on the chat box any material you would suggest I choose/take?
-Could you recommend any material for me and type those recommendations on the chat box?

Do you have any materials that you can suggest that I use to improve my English?
To suggest means to recommend or put forward. Therefore this means you would like the teacher to suggest materials that can help improve your English.
Could you please write in chat box materials you think can help me improve my English?
This means you would like the teacher to give you a list of materials you can use to learn English.

suggestions - this is another word you can use in place of recommendations.
to suggest - this means to offer a recommendation

e.g. I want to go to the theater this weekend. Do you have any suggestions for movies I should watch?

1. Can you type in the chat box the lesson that you recommend for me?
   This statement for the teacher to type the lesson that she thinks is suitable for you in the chatbox.

   2. Please indicate the lesson that you recommend for me in the chat box.
      The word "indicate" means to suggest as a desirable or necessary course of action. Therefore this statement is asking the teacher to suggest the desirable lesson for you and write it in the
      chatbox.

The chat box is a useful tool and aid of communication during online lessons for both teacher and student. For situations where it is necessary to explain the name or title of a book or other educational material, it is perfect if you can use the chat box as it leaves a permanent record for the person you are sending the message to.

"Could" is the polite way to make a request. You can use either suggestions or recommendations since they mean the same thing. I hope that this helps. :)