Your picture has to be shot in a certain way. There aren't any magic wand to my knowledge that would convert a random image to an environment map.
The image format doesn't matter in Blender but files like jpg or png used as environment map are not that great as they cannot contain as much information as .hdr or .exr

I know that I'm nowhere near being a decent Blender user but usually I just set the background image I'm using as the environment image and nobody ever notices. 😝