It is simple to select a study on the WordGo app, providing that you are doing a Personal Study.
First you navigate to the 'Profile' icon which is at the bottom of your screen. You then select 'Course Library'.
You can browse and preview the available studies here. Once you have found the course you want, click on 'Start Course.'
If you need any further assistance please raise a ticket here to contact a WordGo customer support agent.