hmmm … Usually, the way pictures get their borders in Blogger is because of the Blogger template. For example, if you go to my Blog you’ll see a small white border around every picture. I don’t do that – it’s part of the Template that Blogger applies. If you go in to customize Template, then click Advanced at the left, you will see options for images. Play with those and you’ll be setting borders for all the pictures in your blog.

Here’s a video on editing your template:

• blog27.Template Designer #180

You’re right … I see that the Picture Window template does not have the image border option. You need to either pick another template or add the css code yourself. It’s not as bad as it sounds. When you get to the Advanced tab, you’ll see “Add custom CSS” at the bottom of the list.  Here is reference material on what you can do with css in blogger: https://support.google.com/blo…..1954?hl=en

copy this and paste it in – then make your adjustments.

.post img
{
border:3px solid black;
border-radius:10px;
padding: 10px;
}