Adding Ads Under Menu Items (WordPress Site)

Hi All
I hope this is the correct spot to get help for my issue.
I have a wordpress website, and want to add my google text ads directly under my Menu items.

I'm not the most experienced with wordpress theme customisation but am hoping someone can quickly explain where i need to modify my theme/css to insert some text adds.

Note, ads to appear directly under Menu Items (Home, Chilli Seeds, Chilli Readers Reports, etc)