Sourdough Bread

How do I add a photo to the top of my post behind the title “Sourdough Bread”?

How do I edit my image? Is there a way to crop and change the colors right here or do I need to do it elsewhere and then upload it?

I’m experimenting with doing the gallery or multiple photos in a line. It won’t load them all for some reason. When I added the gallery, my larger photo previously loaded turned grey. Now all the photos are grey with slashes through them.