First, I have my own home site where I host my images and hotlink to this blog. There are other options for uploading images to blogger, but I've not tried these so you'll have to try'em out yourselves. I'm using the minima template by designer, Douglas Bowman. My banner image is 649 pixels in width and 149 pixels, height. I'm guessing that different sizes and different templates work essentially the same, just tossing out that information as a possible guide.
I tried copying the code here in this post but for whatever reason, if wasn't working. So, instead... I'm including the image below. It will HOPEFULLY, in the least, guide you to where you can make the changes. You will find the html in your template folder. Oh, and not to confuse you....there should NOT be any birds in your coding... ;)
Good Luck y'all and thanks again for all the incredible comments and emails. **I'm in the middle of a couple assignments right now, so it may a few more days until I can post a new drawing.
EDIT: Please note!! I am in no way an aficionado when it comes to coding html/blogs or anything technical! I just wanted to pass along whatever information I had that might be helpful to others...as I had many requests for it. I'm sorry that I can't upload the actual html for easy cut and paste...the blogger formatting doesn't seem to allow this. Also, it's quite possible this code only works on the template I've used. Ultimately, it's the "header" section in your template that would need tweaking. If and when I learn more tidbits, I'm happy to share! Also, thanks to all of you who added further information in the comments section.