Mystique header image

I’m sure this question has been asked already—and probably more than once—but my searches have turned up nothing helpful in my situation.

On my site, trekosophy.com, I would like to replace the text header with an image, preferably a PNG with transparency. I’m currently using the Mystique theme and I’ve read that I need to go into “Mystique Settings” and there will be an option there for uploading an image for the header. However, I do not see any “Mystique Settings”, nor any options for uploading a header image.

I am running WordPress 3.4.1 hosted on 1and1. I am no stranger to HTML and CSS, but I am new to PHP. Can anyone help me to get a header image uploaded to Mystique?