This is a basic introduction on how to quickly change your logo in WordPress. This is the quickest method, but may be different for some themes.
How to change your logo in WordPress
Before changing your logo make sure that you have compressed the image, cropped it to the right size, as well as taking care to make the upload large enough for retina display. Think carefully about the devices that it will display on and, for goodness sake, please don’t make it too big!
If the method in the video above is not available for your WordPress theme I recommend getting in contact with a developer like CrazyXHTML who can create the CSS/HTML perfectly while optimizing the load time and display options.