Increase Sidebar Widget Area Background

Hello all,

I am trying to increase the size of the gray background of my sidebar widget area as seen on my website https://orange-restoration.com/services/mold-remediation/. To the right where it says speak to an expert with a contact form and below it has testimonials. I want to increase the size of the gray background so I can add more testimonials. I have tried messing with the CSS but I cannot seem to figure it out. Any help would be appreciated. Thanks!