I'm not understanding how I'm supposed to customize my theme?

I do not understand how I'm able to customize my theme? The customization bar is confusing. Where are the options of how to manipulate the website? All I'm seeing is options of changing colors where are the options to put the widgets bar on the right? I need help how do I get help? If I use this theme on my multi site how will the people getting on my website know how to customize the blogs into something the way they like when I cant even figure it out? I need to talk to someone to find the easiest path to where I’m want to go and what I’m trying to build. Is this possible?

I need a simple theme to customize and make pretty so people can get on my website and just blog there hearts out. Are there videos teaching how to customize these themes because the back ends of these themes are different than the 30 other themes that I’ve worked with over the years?