Commerce Set Up (UK)

I wonder if anyone could spare a little time to and try to assist me to set up the commerce within my forum. 

I am currently trying to add a yearly subscription within my forum and seem to have been doing well. However, I cannot seem to follow the guides provided on the main Invision site. 

It appears I have to create some sort of app I need to obtain a Client ID and a Secret. I have logged into what appears to be a part of PayPal whereby I can set up test accounts, but I can't seem to create an app that will allow me to get the required information I need. 

Can anyone who has successfully set up the PayPal system in the UK assist please, it would be much appreciated.