Look into the configuration file for <Directory> tag.
You might see lots of them. Just copy one of them and make changes to point to your directory. Also add an Alias for the directory using the Alias command.
Alias /mysite/ "/path/to/your/direcotory/"
<Directory "/path/to/your/direcotory/">
.....
</Directory>
Now you can access this directory by
http://localhost/mysite