Newbie question - is this possible

Dear All Could someone advise whether this is possible to do using PHP & mySQL and if so could they point me in the right direction or web site. What I want to do is to set up a user/password database and then another database with the users information in it (have not decided what rows to have - say name , address, picked numbers, wins, losses). When a user comes to my site a login box will appear where they type there username & password. This is checked with the 1st database and if OK there details are displayed by getting them from the 2nd database. This way the user can only ever see their own data and no one else's. I can probably work out how to set the login check but cannot plan in my head how to then display that users details from the other database. I hope this makes sense. I have posted this in both groups as it is database related as well. Any comments much appreciated. Thanks Ray