How can I block web crawlers and search engines from accessing and listing an entire website?

The search engines should be easy enough to stop, just put a file called "robots.txt" in the root directory with this in it:

User-agent: *
Disallow: /

For stopping users I would use whatever way your host offers to password-protect directories, or if you're using Apache on Linux you can create a .htaccess file in the root of the website containing:

AuthName "Members only in here"
AuthType Basic
AuthUserFile /path/to/your/.htpasswd
AuthGroupFile /dev/null
require valid-user

and then use the utility htpasswd (in the directory you want to create the .htpasswd in) like this:
htpasswd -c .htpasswd username (for the first time only. remove the -c if you want to add more users)

Thanks a lot nhinds

but can you close the crawler, cause i can't get on a game that i downloaded, so can you close it please