Congratulations for your pi2scart and pi2jamma…
First of all download the image you want to use: (Regamebox, Retropie, Recalbox) Download => http://pi2jamma.info/download
Why use the Images on the site? http://pi2jamma.info/
These have the good config files already done for you. If you want to try it out you are going to face issues people resolved already. This is for very advanced users.
TIP: even if you are a beginner or and advanced user, we recommend to start with the pre build images and continue developing on them. Instead of starting with a new image and redo all our work.
We encounter many questions about customers who try to do it the other way around and 95% of the time you will encounter a problem already fixed in our builds.