Alright, this may be a bit confusing but...
Open the start menu (Or the windows button)
Type in "run" with out the " and push Enter
A little window should pop up, in that type "%appdata%
Double click the folder called ".minecraft"
OPTIONAL but recommended: Right click the folder called "screenshots"
OPTIONAL but recommended: Click "Pin to Quick access" This will let you open up libraries and see the screenshots folder under Quick Access!
Then double click the folder called "screenshots"
Does that help?