[Theme: Celebrate] How to make my theme responsive?

I finished customizing my theme and it is the way I want it to look and then suddenly I found out it looks horrible on any smaller screen. ??

I would really love to make my site responsive but I’m not really sure how to do that?

Could anyone help me out? The site is https://www.successinfailure.com

Thank you very very much in advance! I’ve heard this is a hard thing to do, so if you find the time for this, then I’d be very thankful.