Editing code in a child theme

My apologies if I asked this question before–I can’t find it if I did. I want to change a couple of things on my blog. I know almost nothing about coding, but do know enough to be able to change a couple of colors which is all I want to do. However, I don’t even know how to find the code for my child theme, that’s how new I am. I can see the code for the parent them, but how do I find the child theme and how do I edit?

My site is catholictravelblog I am mainly wanted to change the colors in the Nav menu–white is OK, but when I select an item it turns dark blue like the background. Also, the title of posts is not quite black like I want it, it is a greyish-black. And the “recent posts” column could be a little darker.
I assume I might be able to make those changes, or should I avoid trying since I don’t know anything about coding?