Installing WordPress 2.6 in the root directory

I’ve installed installed wordpress 2.6 in the space provided for my website and when the wordpress folder is put in the www folder I can access it through: http://www.mysite.com/wordpress but if I move the folder to the root I cannot access it through http://mysite.com/wordpress.

As per instructions on codex site, I have modified index.php and put it at the root but could not find the .htaccess file!

Could pls anybody tell me what I am doing wrong ?

Another question is relating to the url of the blog. As I am using the same space as my website I was told by the host to change the dns zone as: http://www.myblog.com CNAME .myblog.com but when I type http://www.myblog.com I just get an ampty or 404 page. Is there a way to make the http://www.myblog.com to point to http://mysite.com/wordpress ?