In order to add Twitter widget to your blog on Blogger, check out the Widget Configurator provided by Twitter. Enter the basic information, and at the bottom of the page you'll get something like this :
data-widget-id="28732342865127936" href="https://twitter.com/bernardshakey">Tweets by @bernardshakey
Copy this code. Next, go into the layout control panel for your Blogger page. Click on "add a gadget" in area of the page onto which you wish to place your new Twitter widget. When the menu for Blogger produced gadgets (aka widgets) appears, select the one for Java/HTML script. Paste the code from into the box. It's that easy.
Your Twitter widget should appear as a nice box with recent Tweets (like my in the column to the right) immediately; however, if you only see a one link hyperlink asking to follow your account then wait. It took mine a couple of hours before Twitter began to send the appropriate information. If you wait for a few hours and nothing appears, go back to your Twitter account's Widget Configurator page and be sure you entered your domain/URL appropriately. If this information is correct and the Twitter widget isn't working, you should probably contact Twitter about the problem (or call a friend who's good with web mechanics).