Choose the model of Google Plus One button
<script type="text/javascript" src="http://apis.google.com/js/plusone.js">
{lang: 'en-US'}</script>
<div><g:plusone size="standard" expr:href="data:post.url"/></div>
{lang: 'en-US'}</script>
<div><g:plusone size="standard" expr:href="data:post.url"/></div>
<script type="text/javascript" src="http://apis.google.com/js/plusone.js">
{lang: 'en-US'}</script>
<div><g:plusone size="tall" expr:href="data:post.url"/></div>
{lang: 'en-US'}</script>
<div><g:plusone size="tall" expr:href="data:post.url"/></div>
Add into your blog
1. Go to Design --> Page Elements --> Add Gadget
2. Choose "HTML/Java Script"
3. Add one of Google Plus button code for Blogger.
4. Click SAVE
Or, maybe you want to add on every blog posts? Follow the steps below.
1. Go to Design --> Edit HTML
2. Check in the "Expand Widget Templates" box
3. Add one of Google Plus button code for Blogger above <data:post.body/> (choose the second if you're using Read More")
4. Click SAVE TEMPLATES
So, easy right, to add Google Plus One for Blogger???