you can see first design in above image the dotted border.The color is red but you can change it by replacing color code.
Adding border around image
First login to blogger accountGo to template and click HTMLPress CTRL + F and search box this codeb:skin>> above it paste the below code there.
Dotted border.post img { border:5px dotted #ff3333; padding:2px; }solid border
.post img { border:5px solid #ff3333; padding:2px; }
to change the color replace #ff3333 with your color code.
Few color codes.
for blue #1a8cff for green #00ff00 for black #001a00save you template and enjoy the style.