Website Idea - What Languages to Learn?

Hi Everyone,

I've had an idea for a website but I don't really know where to start with regards to what language to use for the backend. I presume many of them can do the same things in different ways so i'd like to discuss where to start!

I'd like to create a predictions website for the upcoming Euro 2016 Football (Soccer) Championships. For the past several competitions this has always been done with spreadsheets. People eventually having to manually work out all the scores. This got pretty tedious when there were 100+ entrants. For the 2014 World Cup I automated it all using spreadsheets. This time around i'd like to take it a step further and make a website for it.

Off the top of my head, i'll need the following;

1. Account set up / log in for every user that signs up.
2. The creation of leagues that users can set up/join of their own accord.
3. Take input from the user (their score prediction). From the group stages all the way to the final game and who they think will win the competition. This is all entered and submitted before the tournament starts. Store this somewhere (database)
4. Compare this with the actual score from the match (I would update the site / database / whatever)
5. Award points based on their prediction. 0 for incorrect, 2 for correct result, 5 for correct score, something like that.

Is a website or a web app a better option? I did the Learn Ruby track and got most of the way through the Rails track before hitting a stumbling block with regards to set up and how the todo list lesson is explained.

A bit long but any ideas or suggestions would be great.

Thanks!