How to Convert PNG to JPG (FREE with CleverPDF)

I can't get it to work. It just comes out as a black screen.

I tried this but it still comes out blurry

Best advice ever!😊

IS THERE A MULTIPLE CONVERTER FOR PNG TO JPG?

Thanks for the video. Can you answer this for me. I'm brand new to print on demand and I'm confused. People say I can use canva to download pdf print first but then I still would need to convert it to jpeg. Is png the same as pdf print? And Is jpeg always gonna be 300dpi?