what’s the root of /wp-admin/install.php?

I just tried my first MySQL installation ever, and I believe I’ve done all the steps in the WordPress readme. Now I’m at step 5, “Open /wp-admin/install.php in your browser.” But what do I put before /wp-admin etc? I go to my domain where this is supposed to be happening, davidweigel.com/wp-admin etc, and I get a blank screen. So …

– is there another root for the wordpress backend?
– is there some kind of lag time in setting it up? I just set up wp-config.php a few minutes ago.
– I bought the domain name from joker.com, but I’m managing the account via steadfast networks – another thing I just bought today. Is it possible I need to move my nameservers or something?

I’m really not familiar with this stuff, any help’s appreciated.