PC Gaming League

What I need done:
I need a website designed to collect information regarding stats from an online league that I would like to setup. We want users to be able to submit their scores and also to upload a screenshot of their results (the game doesnt have multiplayer capability and screenshot is our means of checking results). We would also like some kind of administration page where we (the admins of the league) can view all the results for that given week including the screenshots. We would also need a table of results for the users to see who did best that week and an overall leaderboard of who is winner of the league so far.

What I already have versus what the provider will build:
I currently do not have a system in place.

Other context/requirements that providers will need to know:
I'm hoping to keep the site really simple with it being pretty much plain as I will look into customising it at a later date.

Timeframe for delivery:
I would be hoping to have this up and running within 3 weeks if possible, however this can be discussed at a later date.