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.
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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)

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