htaccess rewrite mod for subdomain

[asmith]

hey guys

 

I've searching for a while for this, but it makes me more confused .

 

at the moment, I'm rewriting some urls with this line in my htaccess file :

 

RewriteRule ^key-([0-9]*).html functions.php?name=Search&id=$1 [L]

 

I want to make some subdomains on the site for cities and other information. But I don't know what should I do for subdomains.

 

For example I want this url  : 

http://city1.mysite.com/order1/ 

runs this url actually :

index.php?city=city1&order=order1

 

or

 

this url :   

http://city1.mysite.com/order1/key-57.html

runs this url : 

functions.php?name=Search&id=57&city=city1&order=order1

 

 

I'm confused about what setting I must change in apache. Or how to write such mod in htaccess.

Anyone help? Any tutorial?

 

Thanks in advance