I got an article/tutorial which explains how to include the Google Search API in to the blogs. It was very helpful,but for the sake of wordress blogs users, here I would like to give the steps to include GoogleSearchAPI.
Get your GoogleSearchAPI key for you blog/site.
If you can access the php code of your blog, search for the "wp-content/themes/yourtheme" in the hosting environment. Locate "wp-content/themes/yourtheme/header.php" the file and copy the following content within the head tags.
Now go to the respective php file in the same folder(yourtheme) and place the dic content.