Code script for total comment :
<script style="text/javascript"></script>
<script style="text/javascript">
function numberOfComments(json) {document.write('Total Comments : <b>' + json.feed.openSearch$totalResults.$t +'</b><br>');}</script>
<script src="http://tekkomb.blogspot.com/feeds/comments/default?alt=json-in-script&callback=numberOfComments"></script>
Code script for total post :
<script style="text/javascript">
function showpostcount(json) {
document.write('Total Posts : <b>' + parseInt(json.feed.openSearch$totalResults.$t,10)
+ '</b><br>');}</script>
<script src="http://tekkomb.blogspot.com/feeds/posts/default?alt=json-in-script&callback=showpostcount"></script>
NB: replaced Blue code with your Blog Address.
Follow the steps below:
1. Log in into your blog
2. Click on Layout.
3. Click Page Element.
4. then click Add Gadgets.
5. Select the HTML / Java script, then enter the code.
6. Save.
Good luck