How to Change the Width Of Genesis Sidebar

Hi

I am New to Css and WordPress. I Created facebook page and when i paste the code i can see there is Cut in the Page . To Understand please visit
https://www.androidgamespro.com/

Right Side of Facebook page you can see . I opened Child Theme Css but there are many widths. i dont know which to change. If it is in Blogger whole page width = Posts width+ Sidebar width+Margin width. Can You halp me in resolving this problem.. I dont want to change facebook plugin width as wont look Good. Please help