Putting banner codes on your blog is simple for wordpress blog you can search for plug-in that allows you to put banners in your blog or you can edit your html codes to do that.
For Blogger users if it is google adsense code you want to add to your blog you can do that by selecting add widget on your layout in your dashboard at your design tab , after selecting add widget you will see adsense among the widgets select the type of banner you want and click save, but if it is banner from other websites you can select add widget on your layout and select custom html paste the code inside the big box below the title and submit .
