A4 Thermal Paper

My grandson was able to load software to my iPhone based on instructions received. I am still unclear how to use: download to the app? Find download on app to print? Was able to print the pdf you sent me but does that mean must use pdf format? What about screen prints? Or other formats?

Confused how to use paper. Paper in machine is on a roll. Paper I received is flat. Do I feed it in sheet by sheet or do I need to roll it on the roller in the machine? Please help!

My portable printer has to have thermal paper A4. So it goes very well with the correct paper.