I am enable the pretty url in config.php. I am using xampp, which .htaccess should I replace? I can't seem to make it works....

[KK]

which .htaccess should I replace?

The parent folder of 'couch' (i.e. the folder within which you have placed the 'couch' folder) is considered the site's root.

If there is an existing .htaccess file within this root folder, edit it to place the generated rules into it. Else, create a new .htaccess file.

Hope this helps.