Yes, it's just a simple replacement, but I found it's best to use these settings:
You need to retain the search box and your account box, which appear each side of the logo in EVO. As such, I've found that a maximum logo width of 600px is about the limit. You can go larger, but you'll find it requires a bit more work.
PC computer monitors render at 96 dpi and Macs 72dpi, Uploading a logo at 300 dpi or anything larger than 96dpi is a waste of time. All it does is slow your screen rendering time down even more.
Go to /Admin/Settings/Basic Settings/ Logo (The Logo section is about half way down the page.)
Click Select file and upload your logo.
Tick Enable Resizing (I think this is for mobile phones, but I'm not sure.
Enter the width and height in at the same size as your logo. In my case, 600 x 125. I tried 64 x 64 as shown, but the logo appeared as a postage stamp size image.
Click Upload.
You need to follow Geek_Girl's instructions about cache's but in my case I can get away with just clearing the browser cache.
All done.