The upper navigation bar across the top of your screen is the primary way you'll navigate between Merch Jar modules.
Navigate to: https://app.merchjar.com/dashboard
When you log in to the Merch Jar app, you will be taken to the Dashboard module. The dashboard lists all of your products by ASIN, with the data from all ads and campaigns for a given ASIN aggregated together.
This module is currently under further development.
The Ads dropdown has a module for each level of your ad campaigns: