If you want to load the content of your main domain from another folder, you can add the following redirect to the public_html/.htaccess file:

RewriteEngine on
RewriteCond %{HTTP_HOST} ^yourdomain.fi$ [NC,OR]
RewriteCond %{HTTP_HOST} ^www.yourdomain.fi$
RewriteCond %{REQUEST_URI} !folder/
RewriteRule (.*) /folder/$1 [L]

After this is added, you can upload the site content to a folder public_html/folder. The site is now viewable straight from www.yourdomain.fi.