htaccess

Okay, I need to change my htaccess file permissions, I have been googling for hours and cant work out how to do this or even where the htacess file is located. I am using filezilla, I have made it show hidden files.

First things first, where is the htaccess file located? Im a total n00b!

and secondly what are the best permissions (thoe code things?) to use.

thankyou!