Hi Trista! That is a big question!
You can find the available opportunities on the app under available shops. The description of the shop will give you a good idea of what is to be evaluated. These are posted by Mystery Shopping Companies, and Market Research Companies (not iSecretShop - they are the software) You can then request the shop - some are easier to get than others. When you first start you might need to grab a few that aren't as 'fun' as some of the others - just to get experience.
Once one is assigned to you, it will appear in your assigned shops. You can then see the complete list of instructions there and answer the questions right in the app - it is pretty easy! You can ask the assigned scheduler questions about the shop OR you can put in a ticket with iSecretShop for questions about the app or how it works.
The notifications are set under 'Notifications' in your profile on the full website. You can choose which specialties you have badges for where you want to get push notifications for new shops. Currently this is done only on the full website and not the app.