1.Login to your blogger dashboard--> layout- -> Edit HTML

2.Scroll down to where you see </head> tag .

3.Copy below code and paste it just before the </head> tag.

<style type='text/css'>

#inner-borders a img, #inner-borders a { border: none; overflow: hidden; float: left; }
#inner-borders a:hover { border: 3px solid #0000ff; }
#inner-borders a:hover img { margin: -3px; }

</style>

Note:You can change border color,border size,margin,... But both border size and margin must have a same numerical value.

4.Now add your images as below.

<div id="inner-borders">

<a href="#"><img src="https://1.bp.blogspot.com/_4HKUHirY_2U/SxIRWePfVYI/AAAAAAAAAZ8/MSmCLCmWA8k/slideshow+1+small.jpg" alt="#" /></a>

<a href="#"><img src="https://1.bp.blogspot.com/_4HKUHirY_2U/SxIRhli6o6I/AAAAAAAAAaM/fmkIOf7MPtE/slideshow+2+small.jpg" alt="#" /></a>

<a href="#"><img src="https://3.bp.blogspot.com/_4HKUHirY_2U/SxIRonaYyII/AAAAAAAAAac/ls3j_gSduPk/slideshow+3+small.jpg" alt="#" /></a>

</div>

You are done.

Demo