This website runs on a platform called Discourse. You can view the forum using your web browser either on your PC/laptop or on your mobile devices. If you are using a mobile device (Apple or Android) you can make logging in even easier by downloading the Discourse app.
When asked which site you want to access, enter the site domain imaging.discoursehosting.net. You will then be asked to login with your username and password.
The advantage of using the App is it will use the native notifications on your phone and keep you logged in to make it easier to access and keep track of posts. Have fun 