How to install minecraft forge 1.9?

Hello all… Need some help…
Searched google before posting but can't understand exactly what I need to do to get past my problem after trying to install Forge:
I keep getting the message: "you need to run the version 1.9 manually" when trying to install Forge 1.9.
I've tried to run a "Vanilla Launcher 1.9" first to get it to work… What's a Vanilla launcher? I searched Google and had no luck.
Anyone that has a few minutes, could you explain what I need to do to get Forge 1.9 to install? Relatively new here, so please be kind… And detailed.

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