Help with adding image logo in header instead of text name

I'm new to ELGG and I'm not nearly experienced enough to sift through the files and know what/how to edit all the files. I've been 'winging' it for the past few weeks but I've come across a problem. I don't want to have the site name show up in the header/topbar as the text site name you fill out in the Dashboard but rather use and image that's been created for the banner/logo.

I changed the topbar height and other necessary values(or so I thought) and then I added in the css file the required coding for my image to show up but it didn't work, it didn't load and everything else was thrown off in regards to positioning. So if/when I get the image to work I'll be going back through and adjusting all the positioning values for the main content, elgg main, etc.

I took some classes in html, css, brefily went over some php and javascript but I definitely don't know all I need to know. It's kind of over my head right now, I was hoping to learn as I go and teach myself. I got the plugin/mod installed and working, changed the color scheme, thought it would be simple to add my logo in the header and here I am....feeling like a nub.

Can anyone help?