In Windows Explorer, type %appdata% in the location bar thing near the top of the window. Open the Roaming folder. I'm not completely sure if this works, but first try pressing ctrl+h. If that doesn't show the .minecraft folder, go here to learn how to see hidden folders(folders that start with . ).
on my computer if you go to your pc. then to your users. click on your name and then the app data folder should be right there. click that, then roaming and .minecraft should be the first one. hope this helps.
So I searched for the folder, and this popped up (see screenshot), which means I don't have one, yes?
did you even start Minecraft/Forge before trying to find the folder?
Alternatively you can just click on "open resource pack folder" from within the ingame resource pack selection screen and it'll take you to the .minecraft directory (if you didn't change the game directory for that instance).