Please note: If you get a blank screen after attempting to log in, it means you're being blocked for login behaviour that looks suspicious (e.g. too many invalid attempts in a row). You will be blocked for a certain length of time but can try again later. This is a necessary security measure.
If you don't receive your password-setting email during the registration process (it might get caught in a spam filter, so check your spam folder), just use the "Lost your password?" feature above.
If you still have problems registering or logging in after taking the above warnings into account, feel free to contact support at email@example.com.