Starting my journey, ender 3, can?t save and print

I?m a complete novice but got an ender 3 for Christmas. Assembled the printer and printed the test file dog. Downloaded a model to the Curator software on my laptop then saved it to the micro SD card. When I insert the card in the printer the files not there. I?ve saved it every way I can see to try but it?s not there on the printer. It is there when I search the files on the card in the computer. What am I doing wrong? I know low knowledge users can be a pain so thank you 9n advance.

is the curator software a slicer ?
Otherwise you've probably just saved an stl file to the card and it needs a gcode file that's been processed by a slicer.