Can't open, Extension?

I save it but can’t open, do I need Extension but if I do then how can I download or use the Extension ?
Here’s a photo

Open the project through Pencil2D.
File>Open>Locate the project file

@SandCastleDg Hi, PCLX is not a video or image file. Is a project file for Pencil2D. To open it again, use the Pencil2D program:

FILE > OPEN > Browse folders > Select PCLX

If you want a VIDEO you have to export it from WITHIN the Pencil2D software

FILE > EXPORT > MOVIE > Browse folder where it will be created > type a name > select a file type (MP4 is recommended)

If you want to associate the PCLX to Pencil2D in windows, that’s a bit more tricky. You can follow this guide to do that: