http://your-domain.com/path-to-dolphin/upgrade/

Sometime other web owner make a front

http://your-domain.com - Wordpress then add join now

Now ther dolphin path for join now there is in subdirectory

Sample :

http://your-domain.com/dolphin/join.php

However if you installed dolphin alone

Then its just :

http://your-domain.com/upgrade/

if not then

http://your-domain.com/dolphin/upgrade/