Steam won't open... Help!

Hello,

As a new MacBook owner and user, I really need your help.

I have en new MacBook Pro 13" 2,9 GHz Model no. A1502, and I bought some games via steam.

So I downloaded steam and installed it. But when I try to open the Steam application, it just freezes, on the first steam screen picture and wouldn't load the program at all (See the screenshot). I have tried to delete and reinstall steam, but nothing happens. My question is; Am I doing something wrong or are there some program that you have to install alongside steam to run it??

I really hope you can help...