Just go to blogger.com--------->Edit templates
now .find this

</body>

Taking the necessary steps to nail the process

You will now have to make use of the script which is provided below and paste it before/above </body> tag.
<script>
//<![CDATA[
var custom_pinit_button = "https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEigIIgcOa39T7f7gsqt-RM9-BxYohJfcDYjdvb1mjUEOFJOl1tClrEQ16cgLCx-Uh-4ZDCFeYl9_f0x1izgK__zvBJQunSGWqxeNc0DxosCQFE0uYAqlNsidgwutvRlM6PtBhbxOxxDMw/s1600/pinit-button.png";
var pinit_button_position = "center";
var pinit_button_before = "";
var pinit_button_after = "";
//]]>
</script>
<script src='http://ajax.googleapis.com/ajax/libs/jquery/1.8.2/jquery.min.js' type='text/javascript'></script>
<script id='pinit-img-button' src='http://makingdifferent.github.io/blogger-widgets/pinterest-button1.js' type='text/javascript'>
// Visit makingdifferent.com for more widgets and tricks.
</script>



But, in case you want to place it anywhere else, then replace center with the position you want the button to be in.










var pinit_button_position = "center"