Dear Nailah,
you do not need to create the child theme in this case. You can set your logo in “Appearance > Theme Options > General Settings”. You can find here the field called “Logo URL”. Click here on the button “Upload Image” and upload your logo image from your computer or select an existing image from the Media Library. After saving Theme Options, your logo automatically will replace the Site Title and Description in header.
Best regards
Tomas Toman