Напиши правильно He say he go to France for a holiday and promise send me a postcard with his french address as soon as he find a place stay

Правильно так:

• He says he is going to France for a holiday and promises to send me a postcard with his French address as soon as he finds a place to stay.

Некоторые варианты на выбор:

• He says he's going to France for a holiday and promises to send me a postcard with his French address as soon as he finds somewhere to stay.
• (более формально) He states that he will be going to France for a holiday and has promised to send me a postcard with his French address as soon as he finds somewhere to stay.