Twenty Twelve is a free Blogger template adapted from WordPress with 2 columns, right sidebar, minimalist, posts thumbnails and simple look. Excellent template for blogs about any general topic.
1. Unzip the template file you downloaded (you can use 7-zip or WinRAR for this task).
2. Go to Blogger dashboard, then Theme.
3. Look for dropdown menu and click on it. Then select Restore and click Upload.
4. Select the .xml file from the directory in step 1 and upload it. Thats it, your template should be installed.
Twenty Twelve Blogger Template