This is how the system works generally speaking:
-Once you log into iSecretShop, go to the "Available Shops" page, and browse the shops that are posted.
-When you see the one you are interested in, you click "View Details" and it will open a pop-up window with all the information on the shop.
-Then, you can either self-assign that shop, or click "Request shop" to submit a request for a specific date. The schedulers are frequently reviewing these requests, so it should be approved soon.
If you are at any point prompted to do the following - please do, it is necessary in order to be able to do shops:
*Enter your PayPal email address - you can do that on the "Update Extended Profile" page.
-Once you have a shop assigned to you, you can always view it on the "Assigned Shops" page - there you can see all shops you have assigned, and can click "Complete Shop" on any of them to see the full shop information, the shop instructions, the question, or/and fill out the shop report.
-When you are done filling out the shop report - you click "Finalize Shop" to submit it - it will be reviewed by editors and either approved, or returned to you for additional information (if so, it will appear back in your "Assigned Shops" page).
So, this is how the process generally works on a PC, but the app is pretty similar too.
If you have any specific questions about some particular part of all this, I suggest opening a support ticket through the iSecretShop website or app, and you'll get a response pretty quickly. :)