I would like to put a jpg image file instead of the Web site title text in the upper left corner.
For example, I want to replace the WP Portfolio text with a jpg file in the demo site. Will there be any way?
Do you mean to add a site logo?
First of all Go to Dashboard -> Appearance -> Customize ->Site identity and add your logo image then after
Go to Dashboard -> Appearance -> Customize -> WP Portfolio Theme Options -> Header Options and select header logo only.