CSS: How to Upload Header Image or Logo in Thesis Theme?

We know thesis theme is simple and clear in order to make our site looks pretty we need add image or logo in the header section. Here I am going to explain how to change header image in thesis. First save your site logo as a image file like .jpg, .png, .tif and etc.Then you need FTP software to upload your logo into the site. Here I used filezilla ftb software to upload header logo.