To create a new house, go to Create new house. If you are a new user, toggle the 'New user' button, after that you can fill in a unique username (and optionally a password). Fill in the remaining inputs and click on invite and start predicting (at least one participant has to be filled in to continue) - (if you are a new user, go to your email and verify that you created the house before you can start predicting).
If you have created a new house, you will be forwarded to the betting page immediatly after clicking on 'Invite and start predicting'.
After you have been invited to a house, you will get an email to confirm you want to join this house. When you click the link in the email, you will enter the Death Pool website, where you can create a username for yourself.
You can get to the betting page from within your profile page (go to your profile page via an email you received or sign in via the menu and click on your username - My profile). Select the house you want to access first (press green button with arrow), after that, click on the episode to get to the betting page. Divide 100 points to all characters you think will die in the current episode (or spend all 100 on one character). After putting in an amount, press the plus button to submit your bet. The green circle displays the remaining points you can divide. When you have made your choice(s), click on 'Save' to save your prediction. The big orange rectangle above the search bar shows in which house you are predicting. You will always be able to edit your prediction, until the episode has been locked down.