Sign in on Xbox

Hi, How do i sign in to Viki on the Xbox 360? There is an option to sign in but when i do nothing happens!

I have so many programs on my favourite that i just want to click and watch. I could such for them but i cant remember the names of them always. which means that ill have to log in on my Computer or phone 1st to check the name then enter this on the Xbox Viki in order to watch it on there!

Now this is to long, Please help.