Hello! You won't be able to log in through the profile name. You can only sign in entering your user name (composed by the randon set of letter and numbers) or E-mail and password. Note that user name and profile name are not the same thing. User name is automatically generated and it is unchangeable. Profile name is the name you typed on "What should we call you" on the sign up form. User name can only be seen by the owner's account. Publicity your name is shown as the profile name chosen.