Help?!

Does anyone know how to make one's header photo smaller? I finally made a collage photo in Picnik, but when I added it to my header, it looks so large and way bigger than I want or intended! I've seen collages on other blogs, and they are all normal sized photos in the header. As you can see, if you look above, my header photo is ginormous! And sooo not cool. That's not how it's supposed to look! Please help me (in my sad, puppy dog face and baby voice).

Do any of you guys have any suggestions how to make the collage photo smaller? Also, I know Blogger offers the option to add the header text behind the photo, on top of, or instead of (I think)... is this the option I should use when trying to add the text "SteakNPotatoesKindaGurl: My Culinary Adventure: Recipes and Reviews from a Newbie Foodie". Or should I create the text while I am editing the photo, and save the text into the actual photo?

I'd appreciate any help I can get from you computer whizzes! I know Blogger is supposed to be user friendly, so why am I having so much difficulty? I feel like an old, computer-illiterate lady! :) Help!!!!!

Peace, and bacon grease!