How to make a redirect with .htaccess?

How to make a redirect with .htaccess?

All that i want to know is it possible to do with .htaccess some tricks
(redirectings)
site.org/member/$var > site.org/member/?id=$var like this.
The point is just add the ?id (string constant) before $var.
It's gonna be something like
RewriteEngine On
RewriteRule (or RewriteMatch)... ...
Cheers.