shortcode for sitelogo and siteurl in wordpress? (contact form7)

hi there I'm new to wordpress and I can see that the plugin contact form 7 has a shortcode to output fields. But I was wondering how do I output shortcode of the site's logo and home url?

I read that it has something to do with functions.php, but I get more confused when I see the samples. Can anyone explain to me how I could achieve what I need? Thank you

via Chebli Mohamed