How do you convert an edited video to a file tjat can be uploaded to YouTube?

I downloaded this new program called VideoPad Video Editor. I saved the file & I wanna upload to YouTube. It uploads but doesn't process the video. It says the format is not familiar or something. I tried downloading converters but none of them work. Does anyone know why or how I can fix this problem? I really wanna upload this video to YouTube. I edited a video for my best friend. So can someone please help me? Thanks. :)