Can someone help me?
My temporary solution would be just a plain text file somewhere.
Take the username and password and put it in a comma separated format.
When a user attempts to login:
if username exists, compare the password
if password matches the one in the text file
username does not exist, login failed
However secure/insecure this is, it would be just a functioning prototype that you can come back to later while you work on the other parts of the site.