How do I display Adsense ads below the post title?

If you have a blogger blog then you can add the HTML module under the title of the blog and for some reason you don't have an option to add under the title of the post. If you are using WordPress then you can create shortcodes or functions and place the ad wherever you want. However, do note that sometimes you may want to use either plugin or want to modify the theme. If you are using blogging platforms other than wordpress and blogger then you have to refer to the respective documentation.

Go to the layout of your blogger.com account in the dashboard of the respective blog. In the layout you will find the "Add Gadget", click that and it will open a window where you can find the "AdSense" module, click that and configure the ad you want to display, save it and then drag and drop that configured AdSense module to the right place you want to show your ad.