Redirection from one website to another

I have just optimize my website It is fine. Now I would like to do a redirection from an another website to this one.
The other server where the website is on is not accessible at the moment that is why I would like to this redirection. In a few days I could use this server again. I don't know in this case if it is a temporally redirection or a permanent redirection and how to set it up. Thanks for your help.