Header width and slider questions

[Topic changed to be useful]

So I decided to make a college basketball website, and I’m brand new to this. I’m still in the process of creating the site, but here’s where I’m at so far: http://www.thecollegehoopsblog.com

I have two issues.

1) The more obvious one: I cannot figure out a way to get that banner across the whole site. I at first was just going to use the CHB Logo you see as the header, but I wanted to go with this instead. I don’t know much about coding, but if you show me what to replace with what, I’m sure I could handle that. I’m guessing it has something to do with this part:

#main, .site-header, .top-nav, .footer-row,.info-wrap {
padding: 0 20px;
padding: 0 2rem;

But I tried messing with those numbers and nothing changed, so I really have no idea what I’m doing.

Also, I’m aware that there’s a similar question asked a couple threads down, but I’m gonna need a more simplistic explanation because that conversation might as well be in Arabic. I don’t know where the code goes, what it replaces, etc, and I’d like to start from the beginning before I confuse myself even more. And that leads me to my next question…

2) This is a little less complex, but I cannot get the featured slider image to fill up the whole box. I have the “Post Thumbail Editor” plugin, but I can’t seem to figure out how to use that.

I just started making this yesterday, and I’m a ways away from finishing it, but feel free to throw out any suggestions as far as looks, plugins, etc go. Like I said, I’m totally new to this and any and all help is greatly appreciated. This is all pretty overwhelming. Thanks!