Define directory for subdomain through HTACCESS

I have created a sub-domain and I would like your directory to be a specific folder.

For example:

Subdomain: teste.site.com.br

binder: site / folder /

Here is what I have tried:

RewriteCond% {HTTP_HOST} ^ prueba.site.com.br $
RewriteRule ^ (/)? $ Folder / [L]