Log In/Sign Up, Password box, with user name

This might be an easy one for some but I'm just getting started trying to teach myself some javascript, and I'm trying to slowly make a text-based game, but I'm having problems creating a sign up/log in box, where players can input their character's name and enter a password and access the game, along with the items, etc. that their character has picked up along the way. Ideally, I'd like to have it so that the player's user name and character type appears in the bottom lefthand corner, with a list of items above that, and a map of their present location on the righthand side. However, that'll come later. Essentially what I'm looking for is a sign up/log in box where players can sign into the site whenever they want, using a password I give them, click on a submit button and gain access to the site if the password is correct. I'm also wondering how you can create an account for each player so that they can log in and start playing from where ever they last left their character. I hope that's clear. Sorry. I'd greatly appreciate any help anyone can give me. Thanks.