Now what you downloaded and installed was not Minecraft Nether Update Download for your PC, it was the launcher of Minecraft. So just wait for it to get downloaded and relax. Now it will run its protocol and download the Update files for you, it might take a little time depending on your internet speed also.
So once you finished downloading from your browser, just click to install and voila it’s done and now you can try the snapshot version of the game.
