I could not log in to Galaxy main
First, double-check that you are trying to log into the same server that you registered your account at. You received an account confirmation email with a link when first created – that would be a good place to check. Each public Galaxy server is distinct and independently administered – meaning, an account at one will not be present at another. All users are permitted to create/use one account (and one account only) at each public Galaxy server.
Account emails are case-sensitive so that another item to check for problems (your confirmation email will have the address you used at registration included).
You could also reset your password if you think it might not be right.
If those do not solve the problem, and the account is at https://usegalaxy.org, can you explain in more detail what is going wrong when logging in?
If working at a different server, the above help should also work, but if login problems continue, you’ll need to contact the administrators of that server directly. Not all check this forum. Contact information is usually on the home page of the server and/or in the public server pages listed here: https://galaxyproject.org/use