I used this very nifty little tool at widgetsplus to create a Google+ badge.

• Get your Google+ ID. (the easiest way is to login to Google+ Your ID number is the long string of numbers For example my public profile is http://plus.google.com/109563226758360576597; the ID number is that bit at the end. For more info about Google IDs, visit my post here. 
• Copy your ID number.
• Customize your widget using the widget tool. If your name is very long, you will want to use a width greater than 160 or a smaller font size (it will truncate your name otherwise). My name is georgiawebgurl;I used a smaller font size since I wanted this in my sidebar.
• Basic settings: your Google+ ID, width of badge, and whether you want to include any of your latest posts. 
• Main area settings: Widget colors. 
• Title settings: Change the tag line (the default is Add Me On...)
• Name text: change colors, font type, and size of text relating to your name
• Button: Font size and colors for button (* makes transparent) 
• Bottom text: Font size and color for text at bottom (including the latest posts, if you select 'Include update feed') 
• Click on Get Code to see preview and get the code for copy + paste.  
• Copy code.

Here is what the code looks like in case (yes, you can copy and paste the code, but then you still need to customize it for you!) mbgc='f5f5f5';ww='160';mbc='cecece';bbc='*';bmobc='3b71c6';bbgc='*';bmoc='3F79D5';bfc='1c1c1c';bmofc='ffffff';tlc='cecece';tc='6a6a6a';nc='6a6a6a';bc='6a6a6a';l='y';fs='10';fsb='10';bw='100';ff='4';pc='4889F0';b='s'; pid='109563226758360576597';

Add your Google+ badge to blogger 

• Go to Design.
• Decide where you want to add it on your blog template (mine is left sidebar) and click on Add a Gadget.
• Under Basic Gadgets find HTML/Javascript
• Click on the + button to add it to your design.
• Title (you can leave this blank if you do not want it have any text above your widget)
• Paste in your code from widgetsplus.
• Save your template. Voila!