My heartfelt apologies, but we're severely lacking in that department. Do you have any specific question that you'd like to ask? (this'll also help us out when we do get around to writing documentation)
There is a little bit of information on https://world.mendix.com/display/refguide3/Java+in+the+Cloud
We need to get files onto the server which we use to enhance the HTML email messages. Things like the company logo etc. Picture files like JPG and PNG are used to dynamically change the look a feel of the system. The database upload has a files section but this only allows one file and I am not sure where and what that files is and where it ends up.
Deployment in the cloud is quite intuitive. Request a cloud slot and choose in the modeler 'project/deploy to the cloud portal'. Go to the cloud dashboard an shift your model in test-acceptance-production.