@Ira-Glass Hi, your sentence doesn't quite make sense. You can save a single PNG using the 'Save Snapshot to File' button at the top of the preview window. Or you can render the timeline or a selected region as a PNG Image Sequence.
Or maybe you mean render a series of png files that are on the timeline where each png in the rendered sequence is just one single image -
Either edit the png's on the timeline so they are only 1 frame in length,
Or open Preferences & change this setting to 0.040, then add your png's to the timeline, they will all be only 1 frame in length,
Then when you render as Image Sequence the sequentially numbered sequence will only have one image per number
If you are talking about import a PNG sequence, there is an option to IMPORT IMAGE SEQUENCE. If the PNGs are numbered consecutively, it will import as one video file.