OK...now that our template is set up, we're ready to post BIG pictures.
When I have my photos in my editor, I size them so that a landscape image has a width somewhere between 750 and 850 pixels. In portrait orientation, I usually make the width between 500 - 550 pixels. Size your image as you like, then upload it to Flickr.
Bring up the image in Flickr, then in the choices above the image click All Sizes. This brings up a window with size choices across the top. Click Large.
Below the image, there are two chunks of code that can be selected. Copy the code in Option 1. Option 2 will not give you as large an image.
Return to blogger where you are entering your post. Switch from Compose to Edit HTML. Find the location in the post that you want to place the image and paste the Flickr code there. When you preview your post, you should see your BIG picture.
There's a little bit more to it if you want to arrange the text around the image. If anyone wants that code....let me know and I'll type it up.