If I send a users password to a database table using:

PASSWORD('$userpwd');

when they first register. If I want to check that that user and their password is valid at another login time will I just be able to compare the password they enter the next time they log on with the one in the database to authenticate them. If not how do I do the following:
I want to store user's passwords encrypted in a database but I need to compare these encrypted passwords with user when they login at another time.
Sorry if this sounds confusing.