I'm going to join a new company, please help me to write a letter express a please to join the company and would like have help of everybody in the company.

I would emphasis looking forward to being a valuable addition as a team player to their company
Companies seem to like those catch phrases like what you bring to the table and team player.

Asking about having help of everybody in the company comes of sounding a bit inadequate before you have your foot in the door. Cooperative effort sounds better.

How to write a cover letter?

How to write a cover letter?