Underline color and logo

Hello there!

I have to questions.
1. When you put your mouse on menu (strona g?ówna, blog, psy i ludzie etc.) underline show. Same color we can see if we open any post and look at data. It same color, right? How to change it?
2. I would like to put picture under logo. Something like in momoyo theme. Like that. I mean – how to put something like this picture with soups? It’s even possible in my theme?

I will be so grateful for your response. And sorry for my english ??

The page I need help with: [log in to see the link]