Within the e-mail address, login, or password, you are not going to be able to hack into anything! There is not a system that is in place to help you with the hacking that you want to do as it is nothing that is going to concern other people. The accounts are going to be protected by a password and therefore you are not going to be able to reset the password without knowing the login to the e-mail as well.
There is simply not point in trying to hack into the account that you want to because you are not going to be able to find a way around it. There is no 'how to' guide for something like this as it is a simple website with password protection in place.
You are going to have to survive with not being able to hack into someone else's accounts as this is simply not going to be possible. Not only would you be banned from the site in the future anyway, but you would not be able to succeed in your task, and even if you did, there would not be any benefits from the hacking that you had done as there is nothing for you to gain from it, therefore it is best to accept the fact that you are not going to succeed in the task that you are trying to achieve