Custom Tweet Button


I am a developer and want to make a custom tweet buton for a website .
I saw the page were it is explained how to make this ,but i didn’t understand if i need to put the bird logo on my button or a can make any design i wont for it.
I also want to know if i need any permititon for it. It is itened to have a lot of users that may have click on tweet.

Thank you