Have you ever been able to log in before? If not have you received an e-mail confirming you registration? If not, it may not be approved yet. It is not instantaneous, it is manually reviewed for compliance with the standards.
Warning this is strictly Orions McPhees Opinion, it may or may not have any bearing on events true or imagined
Make sure capitalization and spelling are correct, and that [especially if you are pasting] there are no extra spaces before or after your handle or password.
Once you are sure you are entering your credentials correctly, if the problem persists, try Lost Password again. If it doesn't work, tell us why--what error message you get. Also let us know your handle.
I dare you to make less sense.
Are you a newbie, or do you have access to newbies?