Drakemac2

Hi, I'm new to modding Minecraft (not new to modding itself, I run modded KSP which seems a heck of a lot simpler than this) and all the mods I want to use need forge (or so they say). So I go to mincraftforge.net, click on the recommended version (1.6.4) installer, skip add, save to desktop, run app from desktop, click install client, and an error message pops up saying "You need to run 1.6.4 manually at least once". Help, I tried opening it directly from the download and got the same result. What am I doing wrong? Is it that I run Windows 8 (it was forced upon me unfortunately)? It may seem like a noob question but this the first Minecraft mod I've tried to install alone. Thanks in advance.